Looks like Exile I & II, by Spiderweb Software. Definitely looks like it's worth checking it out
Wow! i loved these games (even if they were shareware) . I thought i was the only guy to know them because they were created for old apple computers, about 6 or 7 years ago.
The concept of the spy is amazing : to sneak in the enemy base disguised in medic through the backdoor and blowing up everything.
The level system gives a little taste of rpg which is quite cool.
A very good alternative to the other FPS (counter-strike, far cry ...) and at least it's free !
I'm not sure but i think that graphics were made by Dave Gibbons. That guy drew "The watchmen ", an amazing comic book. This game rocks.
There is also an easter egg in Broken sword 2 to Beneath a steel sky.