This is a command block creation for Minecraft. It requires no mods or texture packs, just one command block to copy-paste into.
Tired of having nothing to do after acquiring diamond armor and beating the Ender Dragon? Not anymore! With the RPG skills add-on, you can level up your Stealth, Fighting, Fitness, and Archery skills to get special perks and abilities. (Commands shown in video allow for quick leveling up without having to do the work, like for showcases or testing) I will later post an updated version and a full review video if this becomes popular.
To put this contraption in your world, just type in /give @p minecraft:command_block to get a command block, place on the ground. paste in the command below, and set it to "always active"

Not tested in any version other than 1.12.x, should work from 1.9 to 1.12.2

summon falling_block ~ ~1 ~ {Block:stone,Time:1,Passengers:[{id:falling_block,Block:redstone_block,Time:1,Passengers:{id:falling_block,Block:activator_rail,Time:1,Passengers:{id:commandblock_minecart,Command:"gamerule commandBlockOutput false"},{id:commandblock_minecart,Command:"fill ~2 ~-3 ~-1 ~11 ~3 ~2 quartz_block 0 hollow"},{id:commandblock_minecart,Command:"fill ~2 ~-2 ~-1 ~11 ~2 ~2 stained_glass 9 0 quartz_block"},{id:commandblock_minecart,Command:"tellraw @a \"\",{\"text\":\"Thank you for installing my RPG Skills with One Command!\",\"color\":\"gold\"},{\"text\":\"\\n\"},{\"text\":\"Here is a link to my youtube channel:\",\"color\":\"dark_red\"},{\"text\":\"\\n\"},{\"text\":\"www.youtube.com/channel/UC22_oceQxn7PqKuZBujtFsw\",\"color\":\"dark_aqua\",\"clickEvent\":{\"action\":\"open_url\",\"value\":\"www.youtube.com/channel/UC22_oceQxn7PqKuZBujtFsw\"}},{\"text\":\"\\n\"},{\"text\":\"Here is a guide on every skill perk:\",\"color\":\"black\"},{\"text\":\"\\n\"},{\"text\":\"(Currently broken due to Minecraft bug)\",\"color\":\"dark_aqua\"},{\"text\":\"\\n\"},{\"text\":\"Special thanks to MrGarretto for his Command Combiner:\",\"color\":\"dark_green\"},{\"text\":\"\\n\"},{\"text\":\"mrgarretto.com/cmdcombiner\",\"color\":\"dark_aqua\",\"clickEvent\":{\"action\":\"open_url\",\"value\":\"https://mrgarretto.com/cmdcombiner\"}},{\"text\":\"\\n\"},{\"text\":\"Also thanks to Jragon for his youtube tutorials on command blocks:\",\"color\":\"dark_green\"},{\"text\":\"\\n\"},{\"text\":\"jragoncommands.weebly.com/tutorials.html\",\"color\":\"dark_aqua\",\"clickEvent\":{\"action\":\"open_url\",\"value\":\"http://jragoncommands.weebly.com/tutorials.html\"}}]"},{id:commandblock_minecart,Command:"setblock ~1 ~-1 ~ wall_sign 4 0 {Text1:\"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"scoreboard players add @e[type=armor_stand,name=TogAct,c=1] RPGSKILLS_A 1\\\"}}\",Text2:\"{\\\"text\\\":\\\"ON/\\\",\\\"color\\\":\\\"green\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"execute @e[score_RPGSKILLS_A_min=1,score_RPGSKILLS_A=1] ~ ~ ~ blockdata ~ ~ ~ {auto:0}\\\"}}\",Text3:\"{\\\"text\\\":\\\"OFF\\\",\\\"color\\\":\\\"red\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"execute @e[score_RPGSKILLS_A_min=2] ~ ~ ~ blockdata ~ ~ ~ {auto:1}\\\"}}\",Text4:\"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"scoreboard players reset @e[score_RPGSKILLS_A_min=2] RPGSKILLS_A\\\"}}\"}"},{id:commandblock_minecart,Command:"setblock ~1 ~ ~ wall_sign 4 0 {Text1:\"{\\\"text\\\":\\\"\\\"}\",Text2:\"{\\\"text\\\":\\\"REMOVE\\\",\\\"color\\\":\\\"dark_red\\\"}\",Text3:\"{\\\"text\\\":\\\"\\\"}\",Text4:\"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"fill ~ ~-3 ~-1 ~10 ~3 ~2 air\\\"}}\"}"},{id:commandblock_minecart,Command:"summon armor_stand ~3 ~-2 ~ {CustomName:TogAct,Marker:1,NoGravity:1,Invisible:1}"},{id:commandblock_minecart,Command:"scoreboard objectives add RPGSKILLS_A dummy"},{id:commandblock_minecart,Command:"fill ~3 ~-2 ~ ~10 ~2 ~1 chain_command_block 5"},{id:commandblock_minecart,Command:"setblock ~3 ~1 ~ chain_command_block 1"},{id:commandblock_minecart,Command:"fill ~10 ~1 ~ ~4 ~1 ~ chain_command_block 4"},{id:commandblock_minecart,Command:"setblock ~10 ~1 ~1 chain_command_block 2"},{id:commandblock_minecart,Command:"setblock ~3 ~ ~1 chain_command_block 1"},{id:commandblock_minecart,Command:"fill ~10 ~ ~1 ~4 ~ ~1 chain_command_block 4"},{id:commandblock_minecart,Command:"setblock ~10 ~ ~ chain_command_block 3"},{id:commandblock_minecart,Command:"setblock ~3 ~-1 ~ chain_command_block 1"},{id:commandblock_minecart,Command:"fill ~10 ~-1 ~ ~4 ~-1 ~ chain_command_block 4"},{id:commandblock_minecart,Command:"setblock ~10 ~-1 ~1 chain_command_block 2"},{id:commandblock_minecart,Command:"setblock ~3 ~-2 ~1 chain_command_block 1"},{id:commandblock_minecart,Command:"fill ~10 ~-2 ~1 ~4 ~-2 ~1 chain_command_block 4"},{id:commandblock_minecart,Command:"setblock ~10 ~-2 ~ chain_command_block 3"},{id:commandblock_minecart,Command:"setblock ~3 ~-2 ~ repeating_command_block 5"},{id:commandblock_minecart,Command:"blockdata ~7 ~2 ~ {auto:1,Command:\"scoreboard players set @a[score_IsMining_min=1] IsMining 0\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~2 ~ {auto:1,Command:\"scoreboard players set @a[score_IsRunning_min=1] IsRunning 0\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~2 ~ {auto:1,Command:\"/effect @a[score_Fitness_min=500000,score_IsRunning_min=1] minecraft:regeneration 1 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~2 ~ {auto:1,Command:\"/effect @a[score_Fitness_min=400000,score_IsRunning_min=1] minecraft:speed 1 2 true\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~2 ~ {auto:1,Command:\"/effect @a[score_Fitness_min=300000,score_IsRunning_min=1] minecraft:saturation 1 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~1 ~ {auto:1,Command:\"/effect @a[score_Fitness_min=200000,score_IsMining_min=1] minecraft:haste 1 255 true\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~1 ~ {auto:1,Command:\"/effect @a[score_Fitness_min=100000,score_IsRunning_min=1] minecraft:jump_boost 1 2 true\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~1 ~ {auto:1,Command:\"/scoreboard objectives add IsMining stat.mineBlock.minecraft.stone\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~1 ~ {auto:1,Command:\"/scoreboard objectives add IsRunning stat.sprintOneCm\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~1 ~ {auto:1,Command:\"/scoreboard objectives add Fitness stat.sprintOneCm\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~1 ~ {auto:1,Command:\"/scoreboard players set @a[score_IsHoldingBow_min=1] IsHoldingBow 0\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~1 ~ {auto:1,Command:\"scoreboard players set @a[score_IsAiming_min=1] IsAiming 0\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~1 ~ {auto:1,Command:\"scoreboard players set @a[score_HoldingSniper_min=1] HoldingSniper 0\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~1 ~1 {auto:1,Command:\"scoreboard players set @a[score_CraftedArrows_min=1] CraftedArrows 0\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~1 ~1 {auto:1,Command:\"give @a[score_CraftedArrows_min=1,score_Archery_min=5000] minecraft:tipped_arrow 1 0 {CustomPotionEffects:[{Id:2,Amplifier:2,Duration:60},{Id:15,Amplifier:2,Duration:60},{Id:19,Amplifier:2,Duration:60},{Id:24,Amplifier:1,Duration:200},{Id:25,Amplifier:1,Duration:20}],CustomPotionColor:0}\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~1 ~1 {auto:1,Command:\"/execute @a[score_IsHoldingBow_min=1,score_Archery_min=4000] ~ ~ ~ /effect @e[rm=1,r=10] minecraft:glowing 1 1\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~1 ~1 {auto:1,Command:\"/execute @a[score_IsHoldingBow_min=1,score_Archery_min=4000] ~ ~ ~ /effect @e[rm=1,r=10] minecraft:blindness 1 1\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~1 ~1 {auto:1,Command:\"give @a[score_IsAiming_min=1,score_Archery_min=3000] minecraft:spectral_arrow\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~1 ~1 {auto:1,Command:\"give @a[score_CraftedArrows_min=1,score_Archery_min=2000] minecraft:tipped_arrow 1 0 {CustomPotionEffects:[{Id:2,Amplifier:1,Duration:60},{Id:24,Amplifier:1,Duration:60}]}\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~1 ~1 {auto:1,Command:\"effect @a[score_HoldingSniper_min=1,score_Archery_min=1000] minecraft:night_vision 1 255 true\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~1 ~1 {auto:1,Command:\"effect @a[score_HoldingSniper_min=1,score_Archery_min=2000] minecraft:slowness 1 6 true\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~ ~1 {auto:1,Command:\"effect @a[score_IsHoldingBow_min=1,score_Archery_min=1500] minecraft:resistance 1 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~ ~1 {auto:1,Command:\"effect @a[score_HoldingSniper_min=1,score_Archery_min=1000] minecraft:slowness 1 3 true\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~ ~1 {auto:1,Command:\"scoreboard objectives add CraftedArrows stat.craftItem.minecraft.arrow\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~ ~1 {auto:1,Command:\"/scoreboard players set @a HoldingSniper 1 {SelectedItem:{id:\\\"minecraft:bow\\\",Count:1b,tag:{display:{Name:\\\"Sniper\\\"}}}}\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~ ~1 {auto:1,Command:\"/scoreboard players set @a IsHoldingBow 1 {SelectedItem:{id:\\\"minecraft:bow\\\",Count:1b}}\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~ ~1 {auto:1,Command:\"scoreboard objectives add HoldingSniper dummy\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~ ~1 {auto:1,Command:\"scoreboard objectives add IsHoldingBow dummy\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~ ~1 {auto:1,Command:\"scoreboard objectives add IsAiming stat.useItem.minecraft.bow\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~ ~ {auto:1,Command:\"scoreboard objectives add Archery stat.useItem.minecraft.bow\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~ ~ {auto:1,Command:\"/scoreboard players set @a[score_IsFighting_min=1] IsFighting 0\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~ ~ {auto:1,Command:\"/execute @a[score_IsFighting_min=1,score_Fighting_min=50000] ~ ~ ~ /effect @e[rm=1,r=5] slowness 1 2\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~ ~ {auto:1,Command:\"/effect @a[score_IsFighting_min=1,score_Fighting_min=40000] minecraft:haste 2 2 true\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~ ~ {auto:1,Command:\"/effect @a[score_IsFighting_min=1,score_Fighting_min=30000] minecraft:fire_resistance 2 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~ ~ {auto:1,Command:\"/give @a[score_IsFighting_min=1,score_Fighting_min=20000] minecraft:gold_nugget\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~ ~ {auto:1,Command:\"/effect @a[score_IsFighting_min=1,score_Fighting_min=10000] minecraft:saturation 1 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~ ~ {auto:1,Command:\"/scoreboard objectives add IsFighting stat.damageDealt\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~-1 ~ {auto:1,Command:\"/scoreboard objectives add Fighting stat.damageDealt\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~-1 ~ {auto:1,Command:\"/scoreboard players set @a[score_IsSneaking_min=1] IsSneaking 0\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~-1 ~ {auto:1,Command:\"/execute @a[score_IsSneaking_min=1,score_Stealth_min=50000] ~ ~ ~ /effect @e[rm=1,r=10] blindness 1 1\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~-1 ~ {auto:1,Command:\"/execute @a[score_IsSneaking_min=1,score_Stealth_min=40000] ~ ~ ~ /effect @e[rm=1,r=16] glowing 1 1\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~-1 ~ {auto:1,Command:\"/effect @a[score_IsSneaking_min=1,score_Stealth_min=30000] jump_boost 2 1 true\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~-1 ~ {auto:1,Command:\"/effect @a[score_IsSneaking_min=1,score_Stealth_min=20000] invisibility 3 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~-1 ~ {auto:1,Command:\"/effect @a[score_IsSneaking_min=1,score_Stealth_min=10000] invisibility 1 0 true\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~-1 ~ {auto:1,Command:\"/effect @a[score_IsSneaking_min=1,score_Stealth_min=5000] speed 1 1 true\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~-1 ~1 {auto:1,Command:\"/scoreboard objectives add IsSneaking stat.sneakTime\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~-1 ~1 {auto:1,Command:\"/scoreboard objectives add Stealth stat.sneakTime\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~-1 ~1 {auto:1,Command:\"/execute @a[score_IsRunning_min=1] ~ ~ ~ /scoreboard teams join DisplayFitness @p\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~-1 ~1 {auto:1,Command:\"/execute @a[score_IsFighting_min=1] ~ ~ ~ /scoreboard teams join DisplayFighting @p\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~-1 ~1 {auto:1,Command:\"/execute @a[score_IsSneaking_min=1] ~ ~ ~ /scoreboard teams join DisplayStealth @p\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~-1 ~1 {auto:1,Command:\"/execute @a[score_IsAiming_min=1] ~ ~ ~ /scoreboard teams join DisplayArchery @p\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~-1 ~1 {auto:1,Command:\"/scoreboard teams option DisplayFitness color yellow\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~-1 ~1 {auto:1,Command:\"/scoreboard teams option DisplayDarkArcana color black\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~-2 ~1 {auto:1,Command:\"/scoreboard teams option DisplayLightArcana color white\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~-2 ~1 {auto:1,Command:\"/scoreboard teams option DisplayFighting color red\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~-2 ~1 {auto:1,Command:\"/scoreboard teams option DisplayStealth color dark_purple\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~-2 ~1 {auto:1,Command:\"/scoreboard teams option DisplayArchery color green\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~-2 ~1 {auto:1,Command:\"scoreboard teams add DisplayFitness Fitness\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~-2 ~1 {auto:1,Command:\"scoreboard teams add DisplayDarkArcana DarkArcana\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~-2 ~1 {auto:1,Command:\"scoreboard teams add DisplayLightArcana LightArcana\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~-2 ~1 {auto:1,Command:\"scoreboard teams add DisplayArchery Archery\"}"},{id:commandblock_minecart,Command:"blockdata ~10 ~-2 ~ {auto:1,Command:\"scoreboard teams add DisplayFighting Fighting\"}"},{id:commandblock_minecart,Command:"blockdata ~9 ~-2 ~ {auto:1,Command:\"scoreboard teams add DisplayStealth Stealth\"}"},{id:commandblock_minecart,Command:"blockdata ~8 ~-2 ~ {auto:1,Command:\"/scoreboard objectives setdisplay sidebar.team.yellow Fitness\"}"},{id:commandblock_minecart,Command:"blockdata ~7 ~-2 ~ {auto:1,Command:\"/scoreboard objectives setdisplay sidebar.team.white LightArcana\"}"},{id:commandblock_minecart,Command:"blockdata ~6 ~-2 ~ {auto:1,Command:\"/scoreboard objectives setdisplay sidebar.team.black DarkArcana\"}"},{id:commandblock_minecart,Command:"blockdata ~5 ~-2 ~ {auto:1,Command:\"/scoreboard objectives setdisplay sidebar.team.dark_purple Stealth\"}"},{id:commandblock_minecart,Command:"blockdata ~4 ~-2 ~ {auto:1,Command:\"/scoreboard objectives setdisplay sidebar.team.red Fighting\"}"},{id:commandblock_minecart,Command:"blockdata ~3 ~-2 ~ {auto:1,Command:\"/scoreboard objectives setdisplay sidebar.team.green Archery\"}"},{id:commandblock_minecart,Command:"setblock ~ ~ ~1 command_block 0 0 {Command:\"fill ~ ~-3 ~-1 ~ ~ ~ air\"}"},{id:commandblock_minecart,Command:"setblock ~ ~-1 ~1 redstone_block"},{id:commandblock_minecart,Command:"kill @e[type=commandblock_minecart,r=1]"}]}]}]}

Commands combines using mrgarretto.com/cmdcombiner