Isn't Lust Doll exclusively m/f and f/f right now though? Who knows when that game will even get m/m content. On the note of m/m games, uh... it's kind of hard to think of any that don't involve furries of some kind.
I'd have to second Flexible Survival because you can filter out female and herm characters to leave only male critters, but the game is still predominantly furry and monster content with a heavy emphasis on TFs. There is a game mode that heavily reduces the chances of you getting infected and transformed, but it's not 100% guaranteed to not change you from being human - especially if you're looking to play as a bottom (unfortunately being a sub/bottom kinda increases you're likelihood of getting infected). If you don't mind that, you can even pick up the "Submissive" trait that unlocks a lot of encounters specific to that trait for submitting right at the start of a fight.
Anyways, uh... m/m... m/m. Unfortunately, FS and TiTS are the top two I can think of.
Euphorian Tides has some m/m content but it's currently in a hiatus so don't expect new content for it while the creators work on VS.
Venture Seas will have m/m, but currently there's only m/f implemented.
Fleshcult is a fun one, but it can get boring after a bit. The author's also on a bit of a hiatus with it.
Kemo Coliseum is an interesting game. AFAIA, it's still active in development.
Breeding Season used to have an equal amount of m/m and m/f content, but... the game devs decided to rework all of the monster sprites and animations and they ultimately made the decision to work on all animations involving a female player first. Considering I'm keeping very close eyes on this one, I can tell you that they're probably... ~45/50% done with the female player animations. Probably won't be seeing the m/m animations until June or so. Right now there's only one in-game event that has m/m animations and it's with the
Valentine's Day event NPC.
I honestly can't really think of any other ones worth mentioning, haha. If you don't mind commercial VNs, there's always the nitro+CHIRAL visual novels. Coming Out on Top was a fun on too.