roll randomizer add or subtract modifier beat target number. that is the basic system for dice based games. for the d20 system you roll 1D20 (randomizer) plus attack bonus (modifier) and try to beat the AC (target number). in apocalypse world you roll 2D6 (Randomizer) plus stat (modifier) and try to beat 10 (TN).
why do i bring this up well I had ab argument with a player who said combat in pathfinder was boring without using restrictive grids and mini’s because all you do is roll and see if you hit. the thing is that is all you ever do in 95% of dice based RPG’s. no matter how you fancy it up with fluff or add or subtract dice you in the end will roll a randomizer add or subtract a modifier and try to beat a target number. even a game like FFG star wars (the notations make sense when you see the dice) uses this in the end. you roll 2G and 1Y dice (randomizer) plus 2P dice (modifier) and try to get one success (target number).
if you look at a game like the Everyverse RPG they basically just saw the math behind the dice removed the fluff and created a game based on the core statistics of dice rolling. the thing about the player i mentioned above is they wanted to use a system AoO that would add extra dice rolling by adding more attacks in a combat round. also this is a player that would spam every skill they could in every situation which in case you not understand is a lot of just rolling to see if you succeed.
so when it comes to RPG’s remember that the core mechanic is simple and comes down to roll and see if you hit. therefore it is up to the players and Dm to add the flavor to make this simple mechanical rolls amazing. Ex: Player- i roll to hit, DM- great how do you want to hit him. Player- I swing back my mace and come crushing down towards his skull DM- okay you hit so roll damage…ect. too often player and DMs grow lazy and if the rules do not explicitly state something then they will not do it.
Remember the game is only as fun as the group allows it to be. I had fun in DBZ RPG for awhile because the group made it fun. As much salt as I throw at 4e if the group likes it and has fun then they are playing correctly and are doing it right.