The Startup tab: game version and launch options

What this is about
The Startup tab controls how your server is launched: which game version,
which Docker image (the software environment it runs in), and game-specific
options like the player limit.
Variables
Variables are the settings for your game. On Vintage Story they include:
Variable
What it does
Release branch
stable (normal releases), unstable (release candidates) or pre (pre-releases)
Release version
Which version to install. latest follows the newest release on your branch.
Max Clients
Maximum number of players
Start options
Extra launch flags for advanced users
Max Physics Thread / Max Worldgen Threads
How many CPU threads the game may use for physics and world generation
Metrics Port
Port used for Server metrics
Enable Webmap / Livemap Port / HTTP Port
Settings for map and web mods
Change a value, then click Save at the top right of the Variables section.
If you try to leave with unsaved changes, the panel warns you.
Greyed-out variables are fixed and can't be changed.
Each variable has a small reset button that puts it back to its default.
Most variable changes only apply on the next start, and a few (like the game version) need a reinstall. To change your Vintage Story version, follow How to update your server.
Startup Command
The command used to launch your game. It's filled in for you, and on most
servers it can't be edited directly. If your game offers alternatives, pick
one from Predefined Startup Commands.
Docker Image
The software environment your server runs in. For Vintage Story this is the
.NET version the game needs (e.g. Dotnet 10). Choosing a different image
saves immediately.
You normally never need to touch this. If a game update needs a newer .NET version, Vintage Story servers show a .NET Version Mismatch window on the console with a Switch Image & Restart button that does it for you.