RPGs that time forgot... GURPS Time Travel

GURPS Time Travel
Tag line: Adventures Across Time and Dimension
Makers: Steve Jackson Games (1st ed. 1991)

What is it?
A sourcebook featuring 6 time travel campaigns (lost in time, dream travel, time cops, time tourists, temporal nexus and magic ritual) plus a dimensional travel campaign (dimension cops), with full discussion of temporal physics and such.

Neat stuff
-The system for handling paradoxes in time travel gaming is inspired and original.
-I think I got even more out of the cross-dimensional campaign, going as far as putting all my RPG settings at appropriate quantum levels. The physics here are interesting too.
-The glossary of time agent slang makes the setting all the more believable (and fun!).
-Lots of support from GURPS! Most of their sourcebooks can be "visited" with either form of travel, but there's also Timeline, Alternate Earths 1 and 2, and Time Travel Adventures.
-The sample parallel Earths are often sublimely ridiculous: One where the only difference is that Dan Quayle never existed, another where the Monkees became a super-group, the United States of Lizardia, and yes, a Bizarro World. Can you say Sliiiiiiiiiiiiders?

Bad stuff
-The art (in 1st ed. at least) is nothing to call your mom about. Of course, this was a problem with many GURPS books.
-Leaving everything up to the players can be dangerous, especially when it comes to time-travel advantages. Some of these, like Time-Jumper, can be campaign-breaking to say the least!

Quote
"Timesickness as many very colorful nicknames; among the more printable are 'Wells' (as in H.G.) Revenge' and 'The Crosstime Cookie Toss'."

In conclusion
I really like this thing. If you're not intimidated by history, time travel campaigns can be really great. You are intimidated? Go for dimensional travel instead! And while the Time Corps and Infinite Worlds are the primary campaigns (both "cops" games), there's enough discussion of other campaigns to satisfy those kinds of appetites.

How I've used it
Incoprorated in my Shiftworld campaign, it was, in fact, where we left the game (because key players moved away). I basically took the Time Corps setting, but Irwin Allen's Time Tunnel in there instead of the boring transporter pads or whatever is actually used, and managed to get through the entire Titanic adventure from Time Travel Adventures, and part of another from the same book. I had one player who was a History major, and I usually let him fill in details unrelated to the plot, adapting them to the story as I was GMing it. I think the players generally found it cool, but a little complex. I do wish time travel games were easier to pull off and would gladly return to that game where we left it.