LIFE ON TITAN
There comes a time after you've run through the plot a couple of times that you decide to set your own goals. You just want to ignore the plot and do a little exploring and experimenting. This is when you'll really like HardWar's game format. You can't do much exploring in mission-based games.
The key factor is deciding when to break off from the plot. If you don't get the plot started with the Klamp Decoy mission, there's nothing to worry about. The nuclear stuff appears a little later than usual. It's really a pretty dull game.
You can break off following the plot anytime you want, but I suggest breaking right after the Gang Boy mission. To do this you must not go back to Psycho Bob's 1 after the *New Developments* message arrives. If you get up to the Gang Boy phase of the game there'll be plenty of bounty, booty and Fusion Cells to be had. If you go past the Gang Boy phase, you start making enemies you may not want if you're going to play forever. You may also miss profitable opportunities if you continue to follow the plot.
I once played the plot completely through and turned around at the last minute and went to my main hangar. I took a cab to Syd's to pick up my old Moth and just started playing as usual. I don't recommend this as there are many weird things that go on in the game that are just annoying. Try it for yourself if you don't believe me.