This is why CoH2 will have per platform multiplayer

Edit: Mac vs Linux cross-platform multiplayer is now supported in Company of Heroes 2 and its expansions.



It wasn't possible to support cross-platform play for Company of Heroes 2 for a number of reasons; and each of those reasons is itself multifaceted. Some have asked for a technical explanation, so brace yourself for a flavour of the challenges that cross-platform multiplayer support can bring.



Company of Heroes 2 uses a deterministic engine, and relies on clients to generate the same outcome for all gameplay-relevant calculations, like pathfinding, unit positions, spawns and combat.



Any differences in the maths, even at the nth decimal place of precision, will accumulate to a tangible divergence in behaviour and ultimately a disconnect. When dealing with multiple architectures, operating systems and optimising compilers, tracking down all possible differences is a long and complex task.



During development, cross-platform multiplayer was absolutely one of our goals and we invested countless man-hours in isolating and resolving these subtle differences. And although we made progress on some of these issues during development, it's impossible to know how many issues remain and how much more work would be required on ALL platforms to get the title communicating successfully across Mac, Linux and Windows.



Given all this, we took the decision to release the title with per platform multiplayer and keep investigating to see if multiplayer will be possible via a post-release patch. But because of the complexity and the various unknowns, we believe this is unlikely.



As anyone who knows our work is aware, we have a good track record of going the extra mile (or three) to add polish and functionality to our releases. However, in this case the quantum of work versus the low likelihood of ultimate success means that that we have had to compromise.



That's why we want to encourage Mac and Linux gamers to join this Steam Group, which should make finding participants for CoH2 Mac v Mac and Linux v Linux sessions easier.