Split
A downloadable game for Windows, macOS, and Linux
Controls: W/A/S/D to move, Mouse to aim, Left mouse button to shoot,
right mouse button to melee attack.
Left mouse button can be held down for continous shooting.
Melee attacks offer lifesteal and knockback while shooting attacks are ranged.
Code can be found here. https://github.com/DrBlury/Split_Unity2D
Install instructions
For Windows it's just the Split.exe in the main directory.
Other clients were built but I never actually tested those. (don't have devices for these. So you may need to build it for yourself.) Source file is included of course.