I have been talking to musicians about this for half a decade trying to figure out what and what not to do.
Back before Loudr and others made it easy to get licenses, people just put everything up on iTunes or whatever the format was at the time without licenses and every single person I've talked to said they have never received any legal issues. A local vgm musician near me I've spoken to about this has continued to do this for the past however many years hes been in the scene (12+), and they still rake in quite a bit of cash from digital sales for a band that isnt around anymore. His new releases are done the same way, through TuneCore. Never paid a cent in licenses. Understandable back in the day, when you would literally have to email a game publisher and try to arrange licensing, which wasn't feasible for an album with 10 different games.
It is a grey area. If you ask Sam the Neon Orange Knight (or any lawyer), s/he will tell you that you absolutely NEED to get licenses for the songs to even think about releasing them.
It's kind of a scary thought, that you might get sued to oblivion for making/releasing artwork that you put a lot of yourself into. I've never put up my WASD covers on any market besides Bandcamp because I thought I would get "found out" or something, that someone would all of a sudden say "hey you need licenses for that! I'm calling the police!!!!!1!". The only people who have gotten into any big trouble with game music is artists/groups that are doing crowdfunding, and im talking thousands of $$$ [cough OCR cough] (although actually I did remember hearing about this guy a few years ago, a more concerning example). Though I don't think anyone has gotten outright sued for money, they would still be able to leverage their power against you to take down the offending work.
But really, in what way is Bandcamp different from any other digital storefront? You still receive money from fans (sometimes more than on iTunes etc). What about CD sales?
Another band I play in (
redacted ) has gotten both of our releases licensed through Soundrop (formerly Loudr) for digital distribution. I emphasize that because we sell physical CDs at every show we play, but we definitely do not have mechanical licenses for that, partly because it's crazy hard to track, and because we spent so much dang money on the licensing already (not that that is really an argument to lawyers, but we just cant shell out 50%-100% extra when we order CDs so that we can receive some number of intangible licenses for them).
There is a tiny 1% of cases that stand out and make this seem like there is a problem to dance around, but if you browse the literal thousands of video game covers and musicians on YouTube you'll see that the little guys can get away with it, while the big boys who are pulling in a decent chunk of YouTube ad revenue probably cover their asses with licenses because a) they get enough revenue back to support it and b.) they are under more scrutiny from big game publishers due to their popularity.
TL;DR: fuck it, put them up. make a couple bucks like the rest of us. dont worry about the licenses. if someone sues you, go play the lottery, because you will be struck by lightning at any moment. excuse me while I go dump my wasd songs onto itunes