...legal ones or otherwise

wut games trip you teh eff out?

LSD Dream Emulator, Katamari Damacy, Yume Nikki, Any plot reveal in a Professor Layton Game, Stendhal, Active Worlds (RIP, I think.), Knytt, Super Hexagon, Vangers, Jazzpunk, Hypnospace, Antichamber, and I'll finish with Sam & Max.

There are no traces of drugs or booze in this one, but, until you learn how to play it properly, Exanima looks like a drunken fight simulator: You clumsily swing your weapon, trip with everything around, bump into your opponents and even hug them...

Noita has very nice effects when you ingest a lot of whisky or magical mushrooms...

The hangover at the beginning of Disco Elysium is so memorable and well portrayed that you can almost feel the symptoms yourself. There are also enough drugs and booze in this game to keep you away from soberness until the end.

P.S: Your hibernation periods are becoming shorter, ms. Fairfox

What came to my mind is Get Home, a 5-minute free online Flash game from the 2000s. Memorable to this day for the background song. I wonder how feasible it will be to play it in the post-Flash era.

Hotline Miami...

Some of the levels in Psychonauts, like the infamous Milkman Conspiracy level, and that 'running of the bulls' one

Incidentally, last night I survived a magi's' mind attack in Age of Decadence by eating shrooms...

I would say Carmageddon games in general are a notable trip per se but a couple power ups specifically are really crazy: Drugs = distorted visuals, changing colours and Drink Drive = inverted controls.

The Antidote.

http://store.steampowered.com/app/1026080/The_Antidote/

Coffee is a legal drug, right?

Both coffee, and also playing e.g. Team Fortress 2 online or Starcraft or some other interesting game, keeps me awake.

Point'n'click adventures and some slow RPGs have the opposite effect, they make me sleepy, even midday. So they are more like sleeping pills, which are also a legal drug in most parts of the universe, and beyond.

Ironically the spy in team fortress had drug grenades that would cause people that got hit by its cloud to start seeing things that weren't there and wobbled the screen.

https://store.steampowered.com/app/1285670/Post_Void/

My review on Steam lmao,

This game is a better selective serotonin reuptake inhibitor than Prozac. Use with the official unofficial soundtrack on Spotify to achieve maximum effectiveness. Good luck on your treatment!

https://open.spotify.com/playlist/5U5EZgDNJ8HGHdVebHUD3A

The Witcher 1: you can play "under the influence" if you drink too much. It's more annoying than fun.

The Witcher 2: there's a hallucinogenic side quest.

Some games that convey the feeling (not just as a theme):

Katana Zero
Hellbalde - Senua's Sacrifice
Bioshock (I want to say 2, more than 1 actually)
Superhot: Mind Control Delete (somewhat)
Darkwood
The Void
Soma

Vangers looks like a LSD trip.