Open up r2modman and select Risk of Rain 2. (Make sure you don't accidentally select the dedicated server!)
In the profile select screen (Settings > Profile > Change Profile), click Import/Update, and paste the modpack code into it.
Once the modpack has finished importing, click Start Modded and you should be able to join the server.
If you get errors about mod incompatibilities, try to reimport the profile as r2modman sometimes may fail to import mods.
How to Join
Server is visible in the server browser, make sure you enable Show Started Games. If you don't see it, open the console with Ctrl + Alt + ~, then enter the following:
connect serioussaturdays.net:37013
Ruleset
Difficulty: Monsoon
Artifacts:
Command (3 item choice)
Sacrifice
Hunted (survivors spawn as enemies)
Origination (bosses spawn every 10 minutes)
Vengeance (survivor bosses spawn every 10 minutes)
Universe (Stage 6+, all enemies spawn on all stages)
The King (Stage 11+, buffs Mithrix)
Cruelty (Stage 16+, enemies can be multiple elites)
DropInMultiplayer (type /join_as SURVIVORNAME in chat to join midgame)
RiskyMod
Starstorm 2 Unofficial
TeammateRevival
Yeet (click on inventory to drop items)
DoshDrop (press B to drop money)
26 new survivors to use
Playing Singleplayer
Just disable ForceRule and AutoArtifact, and install RulebookUnlocker instead. You'll still be able to connect to the server since these are purely server-side mods that don't need syncing.
Changelog
v24:
Updated SS2U, Cyborg reworked. Can use old version of Cyborg by editing your SS2U config since it's a client-side option.
Hunted now has random loadouts and lower HP.
Updated a lot of mods.
Added Specialist Commando skin.
Swapped GiantParticleFix for DotParticleFix.
v23:
Updated SS2U, Rocket, Driver, Ravager
Removed Bombardier skin since it's now a part of Rocket.
v22:
Updated SS2U, added Nucleator.
Updated RiskyMod, fixed Bandit's Blast not playing sounds/anims online.
Updated other mods. (Left Ravager unupdated since .14 still has some bugs online)
Hunted now has Vengeance overlay texture disabled.
v21:
Added Powerfully Slow Moon (old moon)
Updated mods.
v20:
Added ReturnsCommando, BigRobomando
Updated Pilot, RiskyMod, Driver, NemesisSkins
Removed SteamIDs from DebugToolkit config since it's prone to spoofing.
Added DedicatedServerCrossplayFix
v19:
Updated SS2U to fix Nemesis Invasion RequireFullVoid config option.
Updated Risky Artifacts to remove spawn invulnerability from Hunted umbras.
Updated Suppressive Barrage.
Added ClientHiddenNamesFix.
v18:
Updated SS2U, Nemesis Invasion can now be triggered if you leave Void Fields early.
Updated Ravager, alt special buffed and works online now.
Updated Driver, Pilot.
v17:
Updated Pilot to fix his parachute not showing for other people.
Nerfed enemy Haulers/Potmobiles.
Nerfed Hunted Cyborg umbras.
v16:
Updated Parry so it works better online.
Added Phase4Tweaks (guaranteed item return on-hit with a cooldown in Mithrix Phase 4)
Added Sweeping Barrage
v15:
Updated Pilot to 0.3.7 (adds Returns Cluster Fire option to config, can be changed in-game)
Updated Starstorm 2, fixed Chirr friends not retaining elite type between stages. Friends now keep Cruelty affixes between stages.