I just stumbled across this picture, and I thought: "Damn! I WANT that game!"

Did you have such moments too? What are your favourite game ideas that definitely have to be made?

Looks cool, like the Monkey Island era. Anyways, shouldn't it be "Use" "Tribute" on Big Ugly Demon:
https://www.youtube.com/watch?v=_lK4cX5xGiQ

That should work too! :-D

My Sherlock Holmes Commandos-style game :D

A Police Simulator.

Same!

Sim Morgue

The possibilities are limitless. You have the matter of building, managing, along with cool events and disasters you could add like quarantines, zombies.

https://www.gog.com/game/police_quest_1_2_3_4

Already done.

Also
https://www.gog.com/game/police_quest_swat_1_2
https://www.gog.com/game/this_is_the_police
https://www.gog.com/game/beat_cop

Yeah, that's actually a pretty well covered topic.

I wish there was a versatile but easy to use game creator that allowed to create small dungeon crawling campaigns like the tutorial level of Temple of Elemental Evil, kind of a mixture of NWN/FRUA and the board game Hero Quest, with the gameplay of Elemental Evil and fully customizable dialogue displayed like in BG/PS:T/PoE. Build your own dungeon, but with rich story-telling options as well. Easily moddable, too, so modders could add to the default content.

Alternatively, it could also look and play like Knights of the Chalice (minus the annoying lock-the-party-in-a-dungeon-with-no-apparent-resting-options design of that game).

I was not precise enough. I was thinking of a game similiar to the Grand Theft Auto series. Basically a police simulator in 3D with free-roam.

Here you go, the best German police simulator. :D

L.A. Police Simulator