Amid Evil has aesthetics that remind of a dream or some drug trip. :) Not only the level design is quite weird, but also the lively colors remind of such things. Nevertheless, it's a really good FPS that combines Quake movement with weapons taken from another classic - Heretic. Worth a try. :)

https://www.zombo.com/

The only limt is yourself.

For the mellow trip - Proteus (https://store.steampowered.com/app/219680/Proteus/)

https://store.steampowered.com/app/1388770/Cruelty_Squad/

In "The Saboteur" you are playing an Irishman. Do I have to say more?
;)

For me, it is Dead Space. The game is famous for its horror and fear - this is the most important quality of the game. There are enough screamers in the game, they represent an unexpected jumping out of the closet of a monster, a monster running at you (from the back, for example). It becomes especially scary when a horde of necromorphs runs at you, and you run out of ammo for the cutter, and there are no other weapons either ... It is very good that the game is from a third person, that is, when someone runs to you from behind, you can notice him and expect his attack or something else. I was glad that the game has a wide variety of weapons. In addition to the cutter, you will be given something like a machine gun, rifle, shotgun and bazooka, only in a space style.

the Detective Frog adventures are a stoned dream for children.

YARP!

Gothic. That swampweed has some kick.

how many of these recommenders actually experienced drugs?

visual novels/walking simulators, they will surely make you feel you are being sedated in a nursing home

Yoshi's Island.

There's a level i didn't get past, where every time you get hit with seed (like a dandelion) the speed changes, and everything warps for 10 seconds, and often you'll go back to back several in a row...

Killer 7 is like an acid-trip as directed by Quinton Tarantino.

Even just to page 2 there are clearly a lot of games that reference drugs but can anyone think of games that make you second guess things or feel disoriented?

For example I read A Scanner Darkly by Philip. K. Dick which deals with duel personalities (a vast generaliation but for times sake that's sort of the gist). Intially the book is pretty straight forward but towards the later chapters it actually started making me question what I'd read to the point I'd flip back to the previous page making sure I didn't skip something. It very must added to the story and gets you questioning if the portion you're reading now is real and the other stuff is just imagination, and what about the last 10 pages then?
I've found I like books like this a lot. where they try to confuse time/space/reality to varying degrees in a variety of ways. Catch-22. Several Vonnegut books. American Pyscho in a different way (if you've seen the movie it's fine but it's not the same). A movie like Memento as well, where the medium actually works as part of the disorienting nature in the film.

I love quite a few games that have been mentioned already (Katamari!) but I'm wondering about gaming experiences that make you question if someone slipped somthing in your drink, depsite being in an empty house.