6 Months of Indie Game Development 

Thx :) They do actually expire after some time.

Thanks :) I'm writing the game in C++, that helps. So far the amount of memory needed is even much less than those numbers. Should this change in the future, I'll adjust them.

The general art direction (e.g. simple, readable) is a deliberate choice, but I'm not 100% set on what the final art will be.

The current technical limit I set is 5000 enemies. But I could increase that, should I reach it during playtesting. I will probably not go over 10k, because so many enemies don't fit on the screen anyway. I do grid partitioning, so that every enemy only checks those in close proximity to see if they are overlapping.

@@ykeygames makes sense - I'm assuming that grid partitioning is to determine which enemies are in the same area? As otherwise calculating the distance each time is costly

Yes