A little known piece of trivia: Half-Life was influenced by Turok: Dinosaur Hunter. So much so, that the ladder climbing in the Half-Life Alpha is almost a carbon copy of the ladder climbing in Turok. Even down to the grunts as you climb. There's other Turok influences that can be seen in HL, this is just the one that I find the most amusing.
and yes... I used a beta build of the PC port of Turok to record the footage.
Real Beyta™