What you could implement are sub-options for training-mode to be able to train flying through specific obstacles (rings, walls, blue rooms, etc.), would be kinda cool ^^
It seems that the lag is caused by the level generator or whatever you use, cause the faster you get, the faster the generator needs to generate and it seems that he is not fast enoguh, maybe you could make it pre-generate a bit more before even reaching that specific point. :P
Uhm Sam i tested it and yes its the last level u were on minus 2, and for the boss... hes so easy just shoot in the middle of him while killing the things which come out, and when those squishers come just shoot in a corner in which the boos reflects the ammo so that the squishers will be killed ;) and just shoot on him nothing else xD
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 "Red Remover"){kind=icon}
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Yep totally :) a customisable level generator, in a way