Build 26245744

This update (V0.5.2) reworks the opening of a new game.

- A new game now begins in the fallen city. You read a letter, create your character, then scavenge supplies, gather teammates, and extract from a safe location in the same area.
- Adjusted the starting equipment for custom characters.
- Adjusted the scale of the final military encounter, which now shows how many zombies remain.
- The final military battle and the endless last stand now use separate combat music.
- Adjusted the experience required for survivors to level up.
- Increased the amount of supplies in larger, higher-difficulty maps.
- Fixed ammunition weight being calculated incorrectly and making the backpack far too heavy.
- Fixed an issue where a survivor could spawn inside a building during the final holdout.
- Fixed the double-speed button tooltip in the safehouse remaining on screen after the cursor moved away.

Saves that have already completed the opening can continue as before.