Big Picture Mode and Steam Link fix

Add --single-process to launch options

Thanks to the players who were patient enough to find the solution and share it with us in the discussion forums. I tried adding this by default to the game, but it caused a lot of issues.

Performance Optimization

I've changed a few stuff in the backend to hopefully improve the performance of the game. The only big difference you'll notice is that the tanks no longer leave track marks. This was apparently, a huge performance hit, so I was willing to get rid of it to hopefully improve performance.

Fullscreen scaling and resolutions have changed as well though visually it'll look the same. Because of this, I have removed the seemingly useless option in the settings menu that allowed you to set the resolution manually, which only worked in windowed mode anyway.

If performance hasn't improved, I will explore other options. And maybe reconsider changing the resolution settings again. Please let me know if this patch has done anything for you.

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Mac and Linux versions will be ready once I know that I have a stable PC version going.

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As always, I would like to hear from you. Drop by the discussion forums or comment here; leave your complaints, thoughts, and suggestions!

Cheers!