Cavernous 2 is a puzzle game with idle and incremental elements. In that game, you can passively gain stats to compensate for your lack of skill (in this case, good routes). However, there is a limit to how high these stats can go which is determined by how good the routes are. This makes it kind of redundant, and adds timewalls for skilled players later on in the game when stat grinding is strictly required. I'd either switch the passive stat gain system to not have an upper limit (making idling much more valuable) or replace it with a system that automatically sets those stats to the upper limits (removing idling altogether, though still incremental).
Speedrun Dimensions is a game made during a game jam which involves repeating short incremental "levels" to grind resources that boost your rate of progress in those levels so you can beat further levels. It can get repetitive though, and I'd rather change the system so that you passively gain metaprogression resources based on your best time and replaying the level only serves to lower that time.
Fundamental is a slow game. It's not everyone's cup of tea, but I like it. However, during the quick parts of the game the user interface gets in the way of my speed (and my finger health). It's something I'd want to change, thought I don't know what to change it to.
If you'll notice, the first two issues are similar in nature. I'd imagine most of the changes people will reply with will have something to do with either pacing, the way certain resources are earned, quality-of-life, or how information is conveyed to the player.