Wow, thank you gor the extensive feedback!
First of all, the lack of a true ending is because the game is still in development, the plan is that with all the gems collected you'll be able to open a door to the final area of the game where you can properly finish the game.
There will be more music tracks and I want to implement a dynamic music manager that changes tunes based on elements in each game screen, while keeping the baseline the same. Until, of course, the whole arrangement changes.
As for the various machines in the museum, yes, it's the same game “ported” on those machines, so the only differences will be in the visual style. Like how if you played the original Prince of Persia it would look different depending on the system you played on, like the Macintosh vs Spectrum vs Game Boy vs MS-Dos. While it would've been great to have a different game on each system, it's way out of my time and money budget - 7 games worth of content would take me a crazy amount of time to pull of, since I'm making the game all on my own.
Regardin the Ctrl issue on Mac, I will look into it, you can alternatively use the E key to shoot, I'll put all the key mappings in the help section for the next version.
Thank you so much for trying the game and I really appreciate the feedback!