This is bit of an unusual question, but could someone tell me what the main problem is with Galaxy Rise, one of my games?
Just about every game I try to host like it peters out in the same way. It starts off with a decent amount of people, then with each post, the amount of people posting decreases, until it's just one person or nobody posting.
I suspect it's too open-ended, too hard, and players aren't invested or able to become invested enough.
Players have a bad habit of freezing up when confronted with infinite options or a general goal but no clear hints on how to get there. You'll notice they jumped on the chance to raid the warehouse, for instance, because it was there. They faffed around with some other options- "repair engines," "make new starfighter," and so on, but nothing particularly creative. Now they've got the materials and probably don't know what to do next.
This aforementioned problem is magnified when things are difficult. They've blown their cover, patrols are after them, their easy mark is gone, the haul wasn't enough to get them back on their feet and doing other things... if they're not discouraged, then they're at least probably not swimming in easy ideas. Players are also not known for being especially hard workers, especially for the low-investment format of a suggestion game.
Finally, they might not be invested enough in the game. It hasn't been going on very long, so hitting a snag is more likely to elicit a shrug than the motivation to find a way around it. The game also (at least at the moment) doesn't have a ton of things to feel invested about, like leveling up officers the way they want them to or designing custom ships, which further retards players' abilities to form attachments to it.
In my experience, "here's a situation, do stuff" doesn't work out terribly well for players, and less so in a suggestion game unless it's incredibly silly. The real trick to keeping such a game going, I suspect, is to write and run it such that you end up with an entertaining story regardless of what the players vote for, because otherwise tragedy of the commons and general incompetence will drive it into the ground in short order.