Using FreeDM Using freedm is quite easy thanks to the flexibility of modern ports. You can either:   1. Start the engine with "-iwad freedm.wad" added. 2. Rename freedm.wad to doom2.wad. When playing online I don't recommend this option as it'll make it harder for people to know what Iwad you're using.   With the Legacy launcher go into Game Mode and add freedm.wad to one of the empty slots. Check the radio button next to it and then just launch legacy. No sweat. If you have any problems please post a note here.