This is really awesome! I made a bullet hell survivor-like as well, but didn't get as far with the gameplay. This is really sticky and I like the idea of developing your own mossy attachments. You did an awesome job! I'd be really interested in knowing if you had any resources that you cited when designing and tuning this game. It feels like you got it down well.
Thank you! I mostly just felt it out as I went, but I'd say my past experience with playing a lot of these sorts of games helped with knowing how to tune the mechanics (Vampire Survivors obviously, as well as 20 Minutes Till Dawn; and some bullet hells like Enter the Gungeon, Touhou, among others). Other than that I just have a lot of past experience with hobbyist game development in general so it's largely practice :)
In that regard, there were two main decisions I made that helped reduce lag:
- I tried to design the enemies such that they were less plentiful but a bit bulkier/more aggressive so that there was less "crowd crush" to resolve
- To account for cases where the player isn't clearing enemies fast enough, or even intentionally avoids damaging enemies to amass a bigger crowd, I made it so that any enemy who lives for longer than 60 seconds will start to run away from the player instead - and despawn once they're out of the play area. This did have a side effect of having some enemies run away and then fire at you from way outside of the camera region, which I forgot to fix haha
The TL;DR is that even without a super efficient collision method, some effective game design can go a long way to help circumvent the issue