I recently joined a local game jam with the intent of showing off my 2D engine. Halfway through, I realized I didn't have a way to properly destroy game objects. I realized it after messing up my cooldown timer and accidentally spawning a few thousand projectiles. It's something I knew I had to do that but I kept pushing it back to work on more interesting (but less critical) stuff. Now I am building a very simple hack-and-slash game and adding engine features as needed. Documenting the process here[1] for anyone interested.
[1] https://nik-os.com/agl/17_collisions.html