Well, not only gravity mod can be played trough iccup.com - this is way for many mods, but I'll include reg-file, which will allow to connect with no specific launcher. This is not best way, but I'll hope it will enough good.
Also - I made ZP-Hybrids, and XN-Survivors in my mod. They looks not very good, and need to be reworked, however it were best, that I could for now.