So one suggestion for game play I have is to even out the difficulty variance, and to have it ramp more at the low end. In the forest having an easier first couple hundred feet/meters seems like it would make it more approachable to new players, but overall the variance over the entire game is very high. I feel like a huge amount of the current difficulty variance (seed luck aside, which is a separate thing) is a result of homing enemies.
The spawning algorithm does not seem to take this into account, so sometimes you make have 3 homing enemies (pink spiders and large pink fly's) spawn at once early on and follow, which is very demanding so early for new players, or you may only have 1 per screen or less at higher levels which makes it fairly simple for experienced players. Right now a runs difficulty curve can be all over the place and sometimes decrease as time goes on.
Something that could maybe be done is to spawn homing vs non-homing enemies independently so they are not over or under concentrated on spawn. Also possibly tracking the total number of homing enemies on screen and limiting it based on progression seems like it would help even out the enemy variance.