Impossible Mission II - Technical Steam FAQ 1.2 - 29th October 2020 - 31. May 2025 by Pascal Parvex, https://parvex.org

Enable 256 color VGA mode
In the steamapps folder, find the folder for Impossible Mission II and edit the bottom of the three CONF files like this:

Note that you only change the "IM" line to "IM2_MCGA". This works too with CGA and the other modes. Note: I could not get the 256 color mode to run anymore at the time of the last edit to this guide.

Enable the option to take screenshots and use the Steam overlay
Change the [sdl] section in the three CONF files as mentioned above to OpenGL output like this:
Hat tip to Neozeed for providing this information in the comments.

Title Screen in VGA

Start new game
Press F1 to start a new game. After pressing it, you will see a summary of the previous game. If you made it to the highscore list, you can enter your name (five spaces), then press Enter to start the new game.

Sound
This game only supports the PC speaker, as sound cards were not common back then.

Save a game
Press Alt - S (You get no feedback whatsoever, but it works.). The game supports only one save state.

Load a savegame
You can only load the save state when you are asked for it when you load the game: Press y (z on QWERTZ keyboards) to load the save state; any other key starts a new game.

Pause the game
Press Esc to pause the game, Enter to resume.

Quit the game
Alt + Q