If you're a tester and have access to the game, you can play the demo build before it goes live by swapping to the "demopretest" beta branch, the password is "demodemodemo". To play the real demo once it goes live however, you will have to do some funky wizard magic. I'll make a post about how to do that when its time.
PATCH NOTES:
-Cannon tank attack changed.
-Shed now displays remaining locked weapons.
-Weapon pickup magnetism range no longer affected by game resolution.
-More UI improvements on lower resolutions.
-Neutrino Cannon maximum enemy penetration reduced (8 enemies per projectile -> 6).
-Slam Cannon knockback reduced.
-4 new upgrades. 2 early-game, 2 late-game.
-Gunship behaviour changes.
-Citizens have taken up arms
-New videos.
-Changes to some possible wave compositions for all modes.