Ive seen the film and played the game but when I played the game Rufus died, so how did he survive being blown up and why wouldnt he show his face through the rest of the game?

Possibly he managed to duck out of the way in the last second by hiding under his desk.

Even though Heidegger assumed Rufus had perished in the attack, as he couldn't reach him by phone (naturally - Diamond WEAPON's attack would have destroyed the phone lines to Rufus' office), he probably would have been so badly injured that it would have taken several years to recuperate -a recovery that would take even longer, due to being struck down with Geostigma in FFVIIAC and was confined to a wheelchair.

But that is just an assumption on my part.

we only assume he dies: you don't actually see rufus die at any point. presumably he was so badly injured that he was confined to hospital for the rest of the game.

i realise this is mainly repeated what enkidoh has said but.