I am guessing these options:
Could there be a live stream of Respark and Em8er to engage in a wider audience that showcase the demos of both back to back and some chats.
What if such a planet or area exsisted that those logging into Em8er or Respark could visit to socialise on our first cross game/platform area… is that even possible or too tough?
Heyy, let me begin with the initial question.
I understand that finding out about playtests seems almost impossible, that’s because we keep our community pretty much hidden for now, until there’s much more to show. Fouders were able to participate in a few playtests before, but as we’ve switched engines from Unity to Unreal, we had to redo a huge part of the game and do it more properly. Additionally from the past experience we’ve learned that using a completely custom server solution is the best strategy for being able to handle hundreds of players and thousands of NPCs on one server instance.
It takes a lot of time but we are getting close to something! Once the mining (thumping) gameplay loop is fully functional, we will keep test servers running persistently for anyone to jump in whenever they want while we will be adding updates frequently. Then we can start promoting the game a little more.
As for the question about Respark x Em-8er, we have fans of both projects on our Discord servers, while any collaboration seems impossible due to big differences in concepts of both games, people know about both projects and talk about them and their Firefall memories all the time. 
I guess that even though they have different concepts the common theme is the successor of Firefall and use of Unreal engine.
What if having particular characters appear in each others game such as:
A drone of Respark appears in Em8er with a mini mission and at the end, hints that more help is required in the universe of Respark due to a strange occurance of missing drones.
Then a little image appears to show a bot waving with the offical Respark page to save or check for later.
For the other part the cat lady appears in Respark with a mission and at the end vanishes leaving a cat print with a message to find the portal of the Em8er universe.
After that there is a cat blinking and nudging a yarn ball to check official Em8er page should your curiosity take you or save for later.
Hmm it makes sense to me even have access to some skins from each others games who knows?
Perhaps this is just much dreams to collaborate to push each others plans to success that could be rather good i think… what do you think??? 