What an amazing game, I see a lot of potential here!
I find the game mechanics very intriguing. There are never enough local co-op games to play, and this one has all the potential to be super fun! I've played it alone for now, but I definitely want to replay it with my wife to see how strong our marriage really is.
I had a lot of fun exploring the different levels and discovering some small easter eggs, like the pink cat, although I didn't quite understand what to do with it. The story is simple but entertaining, and in my opinion, puns with doors and detectives are never enough! The characters are also very charming.
I do, however, want to express a criticism on some things that I believe could be improved. Firstly, there are some glitches. The ones I found most annoying concern the camera; while the transition from single screen to split screen is very cool, sometimes it doesn't center the characters properly, and you have to proceed somewhat blindly. This also happens when entering walls, it happens that the camera stop tracking Door. Another issue is that I encountered a softlock while trying to enter a row of walls consecutively with both characters. The detective got stuck in the wall and couldn't get out in any way.
I like the overall graphic design, but I would have preferred a clearer color code. I understand that, in general, brown is for doors, pink is for the detective, and blue is for both, but many elements end up blending together, such as traps, enemies, furniture, and buttons. I think by standardizing the colors a bit, you could have a better visual impact.
The last thing concerns the presence of stealth elements. I'm not a big fan of stealth games, so my opinion might be a bit biased, but I feel that it's the weakest part of the gameplay, at least in the way it has been implemented. Passing through a wall and finding an enemy in front of you is quite frustrating. Furthermore, it clashes a bit with the puzzle parts, which are well-executed and interesting. Puzzles and stealth test two very different player skills: logic on one hand, and quick reflexes on the other. Finding the right balance isn't easy. Especially in the last level, I didn't like having to start all over again because an enemy spotted me when I had already completed some puzzles.
Lastly, I apologize for the wall of text, but I really enjoyed the game and wanted to share a few extra thoughts on my reflections about it XD Congratulations on the excellent work, and thank you for your submission!