Even though we would love to make a multiplayer, it is not easy. It can be done but requires skills we don't have yet and a lot of work.
This is a list of some challenges on making a multiplayer game for mobile:
[*] Synchronism. When processing the game logic on different device cpu, same operations could end up in different results, that means the game state + input could lead to different output in different devices. In order to fix that you have to do a lot of work, depending the type of network architecture you try to use, could be hard to achieve. Also, it is something to consider from the beginning of a project. Transforming Iron Marines to be multiplayer could be really hard to do.
[*] Networking on mobile devices. On PC you can rely on good network most of the time but on mobile devices there are a lot of different conditions, so you have to optimize for bad connection cases, that means to reduce data consumption, etc.
[*] Balance, it is really important in a multiplayer to have a great balance between race/faction/etc. The good thing is that it could improve over time (and with a soft launch or open beta)
[*] It needs a lot of players in order to make it interesting to find matches, etc. Some games don't get enought players on soft launch/open beta and the game sucks when you try to find a match.
[*] Scalability, be able to grow in terms of servers, etc, if the game is a success.
I wrote some
blog posts about multiplayer some time ago in my personal blog, not sure if it helps on anything but it may be fun to read in case you are devs.
Thanks