Worldwide Combos 0.5 is available.
The custom games feature is now available. You may invite whoever you wish to invite, for a given number of rounds, with the rules you want. Note that both players need to have a validated account.
If you don't know who to invite, you may check the suggestion list, which should show you five players that have approximately the same level as you. Be careful though, if you weren't very active recently then it might not be very accurate.
Right now spectating a custom match is a little bit complicated, as you need to watch every round on a different page. Sorry for that. Fixing this is the next thing I am going to do.
I also fixed a few bugs, and made a few optimization, please tell me if it changes something for you (hopefully yes).
In between, 0.4 version was released, with a brand new design for the whole website, as well as new features such as the sprint mode, the warm-up mode, etc.