If you have inconsistent mouse movement, especially when moving multiple mice, make sure the polling rates on your mice are set as low as possible.

You should now be connected to the same game.

Type connect IP and click Submit, replacing IP with the IP you copied, e.g. In all instances, at the main menu, use the ` (tilde) key to open the console. On the first instance, use the server browser to find a server ( Find a server without Valve Anti Cheat, just in case). (If you are using a controller, make sure to also enable Hook XInput in Universal Split Screen). Set Joystick to enabled if you are using a controller. In Universal Split Screen, alt-tab into Half Life so the window is selected, then click ‘Unlock Source engine for a new instance’

GoldSrc Engine games will usually not let you launch more than one instance.

Launch hl.exe as many times as you need.

Open the Half Life directory by right-clicking Half Life in Steam -> Properties -> Local files -> Browse game files… In options, load the GoldSrc Engine preset.Install and run Universal Split Screen: see the quick start guide.

Half Life supports keyboards, mice and controllers so you can use any combination.

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