Onslaught (TC Version) is a standalone mod that allows you to play Onslaught : Resurrected in Open world... It is a mod for Open Doom : hardcore edition, which is already here on gamejolt.
Expect the same brutal gameplay as Onslaught, minus cyborg powers, protagonist voice (sorry the code for that is incompatible with open doom's code), and original music.
With this mod for Open Doom, you can play Onslaught inside Open Doom, complete with Onslaught enemies, weapons, and textures/music. To play follow the instructions below...
The download is a big one, but it's worth it. It should work fine... There were issues with it messing up Open Doom in Beta but I think they've been ironed out with the latest patch for the TC...
Installation instructions:
First of all install open doom : hardcore edition to it's own folder and put your doom2.wad in that folder..
Then Unzip this archive to that folder. Now rename opendoom.pk3 to level.pk3 and run loadons.bat to play...