You were right, it was the Z key. I tried the Enter key and the Spacebar because that's usually the Start equivalent. It does work with the keyboard.
Viewing post in Project V1 - Space Vampire Thriller jam comments
It crashed again. This is the last line of the Ogre.log file (the other lines are unrelated and from minutes earlier):
23:08:47: Ogre::RenderingAPIException::RenderingAPIException: Unable to set light details in D3D9RenderSystem::setD3D9Light at C:\OgreSDK\Ogre3D\ogre\RenderSystems\Direct3D9\src\OgreD3D9RenderSystem.cpp (line 247)
It's apparently a problem with Direct3D, so it's just a Linux / Wine problem and not a problem with your game.
I'll investigate the issue later. I added the game to a private collection because now I'm curious about the lore and all that cool stuff.