My trick involves how I build my collection (and also prune my collection from time to time). I have pretty decently difficult OCD, and my collections are a pretty major thing with that. so I need a way to differentiate between games I like, and games my OCD demon wants me to have for insane reasons.
Anyway: I start by not having a bunch of similar games. because, for example, if I want to play something similar to the PS1 Tomb Raiders, it's better to have 3-4 options than 12.
The way I filter the options down is what I call the 2 folder method:
I imagine 2 folders, literally labeled 1 and 2. Folder 1 contains all the games I absolutely love. 2 contains everything else.
next I go to folder 2 and further sub divide. games I'm actually interested in playing, trying, whatever, all go into sub folder 1. sub folder 2 gets everything else. I then just don't bother with the sub folder 2 games at all. my collection ends up being made from the folder 1 and sub folder 1 games.
sub folder 1 games need to have a concrete reason to go there though. so no "well, I like that series" or "I liked this when I was 12" or "this one is popular" or any of that. because that's not good enough. If I can't think of a real reason, it's not worth it.
being able to articulate why you like games, and also be honest with yourself (and in my case recognize OCD thoughts vs sane ones) is vital for this method to work
I also keep all my roms and PC games in seperate, labeled folders, so it's much easier to do this with 40 neo geo games, 60 NES games and 80 PS1 games than it is with everything all at once
as for picking what game to play, it's all about steps. go from big to small. make decisions.
so what am I feeling troday? fun, engrossing, shooting, what?
ok, fun. what's fun? Racing, platformers, tetris clone?
platformer. so which series? crash. sonic, mario, DK...
yeah, DK. so 1, 2, 3, land, returns or tropical freeze?
Then you're gonna have to just decide. but this is where filtering helps. so lets say you dropped land, Freeze and 3. now you only have to pick between 1, 2 and returns. which is much easier.