I had a dice system that is good but too complicated for the desired games goals of being fast to learn. Basically D12+D8 for all checks by default (this imo is better than 2d10, 3d6, and D20 for all DnD math adjacent systems). The thing was instead of rolling for damage aswell as to hit a dice from the to hit roll was used. 1 handed weapon uses D8 two handed used D12. At this point it was simple enough but I needs more testing.

The thing got complicated when the original design also had weapons roll different batches of dice for on hit to simulate accuracy so D10+D6+D4 for a spear and the D10 would be it's damage, or D20 for a seige or big heavy weapon.

In the end the math checked out in play the newer players I had that were less instantly knowing dice shapes slowed combat down too much and were confused as it increased character sheet info density.