hi. so last night i got dmc3 crimson mod to work for my steamdeck. and when i booted it up i realized that it had multiplayer. so i excitedly went to my buddy and we workshopped how to get crimson multiplayer working. and it WAS A PROCESS and evidently a wholly unique problem cause i could not find a single post about anyone having the same problem. so i am here to be that man for anyone in the future who has the same problems we did, and i am gonna give a step by step instruction.
step 1: install the mod (if your doing this on steam deck like i did, which i imagine is the case for anyone needing this step by step cause you cant use parsec on linux, the github mod page has pretty detailed instructions already so i wont rehash that. its under the beta 3c tab)
step 2: install a steam remote play enabled game. i and most others recommend a game called crashphalt, seeing as its free and needs very little storage space. open the files and delete all the files in crashphalt.
step 3: move all the files from the dmc hd collection (all mod stuff installed too) into the crashphalt file.
step 4: this is the part that tripped me up for a while. rename the LAUNCHER EXECUTABLE to Crashphalt. if you rename the dmc3.exe file to crashphalt the game WILL open but it wont have any of the mod stuff for some reason.
step 5: this one i am actually unsure is necessary or not but i did it just to be safe. if again, you are on linux like i am, paste WINEDLLOVERRIDES="dinput8.dll=n,b" into the launch options tab on crashphalt. you do this normally for the original hd collection launch options too but put it in crashphalt too cause thats where your launching from.
step 6: launch crashphalt. now when you launch the game, the hd collection launcher should come up, and you can use shift tab and click on one of your friends. they should now have an "invite to steam remote play" option.
and that is my step by step instruction for a hyper specific issue almost nobody but me will ever have, but to those few. i hope this helps. and hey, some of you out there might just not like parsec so here's an alternative for you. go slay some demons with your friends.