Truly dynamic weather effects are a pretty interesting game design challenge; which basically nobody has tackled fully. Stuff like flash flooding, realistic snow, collision on smoke or clouds, etc is a ways out yet, buy I am
very much looking forward to seeing games that try to deal with it. Maybe PS3?
Miscellaneous things I'd think would be do-able for PS2:
- Lightning strikes, could fry vehicles or structures, insta-kill infantry? Could be triggered on purpose by sneaky infiltrators using some specialty device?
- Snowflakes hitting a hot gun muzzle/vehicles exhaust could flash to steam. That would be a pretty neat effect, but then you'd have to keep track of object temperatures... so it could just be optional client-side visual toggle.
- Slippery roads, especially if we've got proper physics. Just turn the friction down and add mud spray. PS muddin' could be an e-sport.
I know I'm forgetting at least one other thing I had thought of earlier. Anyway, whatever, it's mostly a question of whether the devs think the resources needed to pull this stuff off are worth it. My gut feeling is "nope". Once the game is out development will consist of new things that could be sold in the game-store.