The default models broke out of the scene editor. Hold the grey-box arena, merge commits between waves, and survive whatever the patch notes do next.

• 9 kinds of broken content come for you: Placeholders, T-Posers, Shader Compilers, Null Refs, Breaking Changes, 1GB Exports, Hotload Clones that split in two, ERRORs that burst into their own letters, and the QA Dummy, who patches wounded enemies back up.
• Two bosses, three phases each. THE REWRITE (v1.0 → rewritten → rewritten again) and SOON™ (ETA: soon → 2 weeks → TBA).
• 8 weapons, 0 balance passes. The Breaking-Change Shotgun, the Unoptimized Launcher, the Deprecated Laser, the Physics Gun, the Tool Gun… and just a crowbar.
• Merge commits between waves. Over 20 upgrades like Multishot.dll, Garbage collector, Memory leak, Orbiting floppies and Ctrl+Z.
•  26 patch notes rewrite the rules every wave. Bouncy bullets, Big Head Mode, sv_gravity 200, models that failed to load, hotload on save…
•  5 release channels. Stable, Nightly, Debug, Experimental and Sandbox.
•  9 arenas. Four dev grids and a few very familiar sandbox maps.
•  Everything is a prop. Spawn props, grab and fling things with the Physics Gun, tie balloons to your problems with the Tool Gun.
•  Developer console (F1). sv_cheats, god, noclip, give, ent_create, bot_add… Cheated runs don't count.
•  19 achievements and online leaderboards for high score, most kills and best wave — all time and this week.