Roll-Over

Roll-under systems are cool, however they have a “bug”: your stats go up, but you’re hoping for low results. In roll-over, you want to roll high because your stats represent bad stuff that have to be overcome (Weakness, Fear, etc.) As you level up, your stats go down since you’re reducing these shortcomings. This system seems to go well with horror games.

Gear 20

In this system you’re usually rolling 1d20 + modifier versus a target number. During combat, as the stakes rise, your modifiers go up and your die size goes down, representing that you’re more becoming more focused and more powerful. This system seems to go well with superheroic games with mid-combat transformations (Super Saiyan, Gear 2, etc.)

Karmic Dice

No one likes rolling low all night… So why not balance things out? In this system, your target number is always the last number you have rolled — fumbles are almost always followed by easy wins, and vice versa. Can this be abused by players? I’m sure it can’t. This system seems to go well with narrative games.

Two-Hit

Here you roll two dice and count how how many “hit”, i.e., meet or beat the target number. You get a failure on zero hits, a mixed success on one hit, and a full success on two hits. This system seems to go well with games that want both degrees of success and GM-set target numbers.

Lock ’n’ Roll

This system requires dice with half “miss” faces and half “hit” faces (like VtM dice.) Then you just need to roll four dice and count hits: zero or one is a failure, two is a mixed success, and three or four is a full success. When rolling with advantage/disadvantage, lock up to two dice on a hit/miss and roll the rest. This system seems to go well with dice goblins that want maximum legibility.

Nudge

This system also requires dice with half “miss” faces and half “hit” faces, here called “nudge” dice. Now roll a regular 1d20, but include one or more nudge dice when rolling with advantage or disadvantage. On advantage/disadvantage, each hit on the nudge dice increases/decreases the degree of success by one. This system seems to go well with games that have many degrees of success, but want to avoid addition at all costs.

The Ur-System

Flip a coin. You succeed on heads. This system seems to go well with games that could not give less of a f***.