Totally new? That's very tough. A lot has been done already, but that's beside the point.

Yes, it is possible to create new and different sounds by simply tweaking oscillators, filters and envelopes, but it takes some imagination and a lot of patience. The more complex your synth engine (more oscillators, filters, modulations, samples to choose from, effects, etc), the easier it is to create something really new, but at the same time it is also easier to create something really afwul. Just try. I think the CS1x (which is not an FM synth) is good enough for creating nice sounds.