space captain said:wasnt the main story arc of fallout and fallout 2 pretty linear as well??? i mean, there was the main story arc, and then a whole shitload of optional side quests around the main arc...
Nope. Fallout 2 was, but Fallout wasn't. The ending to Fallout was typically get the water chip, destroy the military base, then kill the master. However, you could destroy the military base, get the water chip, then kill the master.. Or you could kill the master first, get the water chip, then destroy the military base.. Or you could ignore the water chip and do either the military base or master in any order if you got it all done in under the time limit for the water chip quest.
There also is no story arc between leaving the vault and finishing off the Unity. There were lots of side quests where many of them offered clues about the Unity's existance and what they were doing, but they were all optional and could be done in any order.
Geneforge was the same way.