Yeah, I keep wishing SS13 would be a little more serious and have more longevity. I played it to death in 1 week, but the constant restarts made me loose interest.
What I would really love is SS13 where you build the space-station. Start with basic stuff, have to import food, keep building new rooms, isolating them... eventually getting machinery that would allow you to start getting food and/or other stuff, etc etc 
Baystation12 can lasts for 6 hours easy. It's very RP heavy though, so it can get tiring after a while.
I remember a meteor gamemode we played once where the meteors were bugged and never stopped coming. They annihilated almost the entire station before the admins stopped it, and instead of restarting the server, we kept playing. We evacuated all the civilians to the mining base, gathering supplies on the way. Then we came back after the storm and began rebuilding. We actually managed to fully repair several sections, including arrivals and parts of medbay. It was great fun.
