DOOM: The Gallery Experience Walkthrough
A quick guide to the medals in this game.
Inquisitive
Interact with everything! Even art in secret areas.
Both sculptures/statues and tapestries/paintings/etc.
Tip: Go through items sequentially if you can. Look around and backtrack through rooms to make sure you don't miss anything - it's easy to!
Hoarder
Pick up everything! Even items in secret areas.
Both cash and cheese/beverage.
Big Spender
Use all money you have before you exit the gallery.
To do this you need to buy items with a total cost equal to the exact amount of money you can collect, which is 999.
You can probably combine different items for this, the ones I went with were these:
DOOM: TGE - 257
Mini Sarcophagus - 200
Nuihaku - 114
(final three items on the left side of the room)
Mini Neptune - 428
(first item on the right side of the room)
Explorer
Find all secret areas!
There are the three of them, the same as in E1M1 in the original game (Google 'E1M1 secrets' if you want a video).
1. Interact with the wall that has a different color on the right on your way towards the exit, right after the water room.
2. When you've gone into the exit room, backtrack, and an area will have opened up to your right when you get back into the water room.
3. Go back to the very beginning and check the door you started the level by, it'll now be open, with an extra painting inside.
Escape Artist
Go straight for the exit, move quickly and hit the final switch in less than ~20 seconds or so.
Plastered
Drink everything.
If you're going for the 'Hoarder' medal this is easy to do at the same time, keep hitting the shift key as you move around to keep indulging; not spend any extra time drinking through everything when you're done with everything else.
Connoisseur
Just keep playing, move around and let time go. :)
If you're aiming to get all medals in the same run you probably won't need to roam around aimlessly for this one, though that said you may be able to get this just by keeping the game window open and letting time pass; not actually interacting at all. I haven't tested.
Secret medal (Vintage!)
Play the game with DOOM music (toggle in menu).
Cheese
This is not a medal. There is in fact nothing at all to incentivize the collection of cheese, even with all those drinks it's left uneaten!
The cheese is meaningless.
That is all.