Now that voting has finished I have made an update to CtrlX adding lots of small changes as well as Mac support! 

Update 1.1

• Mac support.
• Reworked yellow weapon.
• Tweaked blue weapon.
• More music.
• Settings menu - game now works at any resolution and aspect ratio.
• Pause menu (press 'p' during gameplay).
• Better transition between menu and gameplay.
• Lots of bug fixes!

I was also able to give the game a test on a VM and I can confirm it works with Windows XP. I've so far yet to find anything it struggles to run on but I would love the chance to try it on some older hardware ;P