So, im really interested in this game. Arena horde fps are my jam, and this one is on sale for 2 bucks right now. Was wondering if there is a windows 10 workaround before I open my wallet.

Well, you could try to use DgVoodoo 2 and see if it works.

Direct link:
dgVoodoo v2.53 (released: 11.09.2016)

The promo will end in about 10 hours ...

Thanks for the tip, homie. Since the game just went on sale again, I think I'm gonna try this. :D

I know it's old, but I have Windows 10 and Painkiller just works. There's no need for any workaround. They just need to update the compatibility info I guess.

That is only true with DRM-free versions of Painkiller. DRM-infested versions (i.e. the boxed copies as originally published by DreamCatcher) will not work on Windows 10 because Microsoft deliberately prevents games infested with SecuROM from running on Windows 10.

Having said that, unofficially modded files can be used to workaround that problem and make DRM-infested versions of Painkiller run on Windows 10. However, when I did that (I have the original DreamCatcher versions of Painkiller and Battle Out of Hell), the in-game interface would not recognize my old Saved Games. Therefore, my Saved Games data became useless (which means I lose a ton of time, energy and accomplishments).

I re-purchased the games on GOG to see if that will allow me both to run Painkiller on Windows 10 and have the games recognize my old Saved Games that were made with the DreamCatcher versions on my old computer in Windows XP. I'll be very happy if the GOG version makes my Saved Games work again.

On the other hand, I'll be very upset if the GOG version doesn't make my Saved Games work again, because that was the last option I had left to try (I won't be upset with GOG though...rather, I'll be upset with Microsoft/DreamCatcher/SecuROM for causing my original games not to work).

But anyway, to return to your original point: Microsoft could never call Painkiller compatible with Windows 10 since many legitimate copies of Painkiller are not, as a direct result of Microsoft's choice to disable them from running.

Good to know. That's why GOG.com is the best place to get your PC games. I got Painkiller here for 2,39 € without knowing what it was. Incredible value. My advice to anyone owing a DRM infested version is to delete it and simply rebuy the game here, and be all fun & play without going crazy trying to have semi-illegal work-arounds to work.