Really fun game! I enjoy it a lot. I've recommended it to my friends. Here are a few quality-of-life comments/suggestions:
1.) Allow us to use the numpad on our keyboard to dial the phone. Dialing the rotary phone was fun and retro at first, but I got sick of it pretty quickly. I know it's not historically accurate but who cares? It makes thinks clunky and slow. Speaking of that...
2.) Allow us to summon the DDD by just pressing the button. Having to press the button AND call them is redundant and slows the game down.
3.) Allow us to change the length/duration of a game. Currently I believe it sends about 10 total people per game. It would be nice to have longer games or 15, 20, 25, 30, etc.
4.) Add Nightmare-level difficulty with "normal" people too. I was hoping that Nightmare difficulty would just be the normal people but with crazier doppelgangers + immediately being killed. The current Nightmare mode is fine too, but maybe call it Monster Mode or Evil Mode or something?
5.) Add more variety to the ways that doppels can trick us, and more subtle ways too. I've played dozens of games already but only seen doppels with the wrong ID numbers 1 or 2 times. I also saw a doppel with a misspelled name once... that would be another good, subtle clue if it appeared more often. Another one would be simply making them get other facts wrong, like giving the wrong job, the wrong apartment number/floor, etc. Also, minor visual clues like a twitching, blinking, drooling, etc. Lots of fun new ways to make doppels and to have them get discovered!
6.) There are a few minor mistranslations for English that I've noticed. At first I thought these were clues that people were doppels but after seeing them enough, I realized they were just simple grammar mistakes. I don't say this to be rude! I am willing to send you a list of these mistakes if you like, free of charge. I am a native English speaker with a university degree in English language and linguistics. Please let me know if you'd like any assistance fixing some of the grammar in the game.
Thanks again for this game, it's really fun! Doppelganger/impostor horror is one of the creepiest types of horror imo, so thanks for creating this game!