I remember those, really ahead of their time. I'm assuming this will be single-player, so you could look into creating some grid-based LOS systems using events, for player FOV, grenade area etc.
Here's a really quickly implemented grid LOS done for a game jam (click on Stealth Chess):
If you're using a tilemap for the levels, Easystar is a good alternative to the stock pathfinding behavior:
For proper raycasting in C2 instead of messing with the LOS behavior or fiddling with sprites then the Chipmunk physics behavior is the way to go:
Let me know if you want some pointers for that one, it can be tricky to figure out.