Though lacking in polish, this is definitely the most re-playable and gamey expansion kink game there is. You did a really good job and as far as the initial scope of it being a single player, kinky L4D with a level editor it's pretty much perfect. A new patch brought new bugs (namely that the Sniper Rifle's projectile loves to just phase through infected at random) but overall you have my applause for sticking with this project for so long in any case.
I have only one suggestion for something new to be added, and that's some sort of scoring/proper arcade mode. As it is, I feel like with the way the game is currently set up that I'd want to replay the levels for better scores or faster times. That is itself fun to do, but the game isn't really built to accommodate that. Carbon-pop lasting forever means that you can't drink it if you want your scores from other runs to be equivalent, which wasn't itself a huge issue until I realized that consuming the golden bottle at the end of each game also counts as a drink consumed, permanently offsetting my scores.
It's ultimately just quality of life re-playability fixing, but some way to set your Carbon-pop consumed back down to 0 and a scoreboard of past runs accessible on the main menu would be really cool. Additionally the ability to set weapons back to their default capabilities would make for fun challenge runs without the need for resetting entire save files.
Again, though, my hat's off to you for making something this completed anyway. I've gotten by this far just keeping down a notepad file.