I'm sure I played it around 10 years of age which is 2013 but the game itself I think dates back to 2000s and possibly further back.
Genres: Adventure(I'm sure of it), Puzzle elements, Dungeon(kind of).
Graphics, perspective: Side-view, I guess you could call it 2D but it's not pixelated that's for sure.
The main character I think looked like a cowboy or something similar, kind of like a thief cowboy or criminal in general. You control him with the arrows on the keyboard ( not sure about W,A,S,D) You had the option to jump with the upper arrow.
There were monsters roaming around and all I remember about them is that there were spiders(snakes too I think), not sure about others. The atmosphere was kind of darkish, not many colours but the monotone ones - like brown.
And the objective as I remember it - you had to find and collect specifically coloured keys(bronze, silver, black etc.) to unlock specifically coloured doors. I am not sure why maybe progression but you had to unlock them. You could die pretty easily with a small number of lives - kind of like the Mario style one. I am not sure if you had a chance to fight off the enemies, and I think there were some kind of traps but I'm not sure.
At the time I was a little kid so I didn't really know the developer's name or the exact year of publishing the game, it's just a game my dad installed for me on my old PC, a good memory.
Thank you in advance.
Have a nice day!
