Wow!

[kasparov5]

I am finishing up my first playthrough of half-life and dang surface tension is a long hard level. Incredibly long actually, but a ton of fun. Are later levels longer/harder?

 

[Kyzr]

Compared to the lambda labs and xen, surface tension is nothing. So ya the game gets a bit harder in my opinion.

 

[Tony]

It's less "taking on the entire military" and more "mildly frustrating jumping puzzles" but yes, it gets harder.

 

[McGooTheWise]

You will meet some new aliens in about 2 levels that will frustrate you beyond belief. And then another monster alien to shit ya drawls to.

 

[kupocake]

'On A Rail' and 'Surface Tension' have the highest amount of maps in the game, so no, there's nothing really that beats Surface tension for sheer scale. Most of the following chapters are 1-4 maps long, I think? However, The Lambda labs levels are quite non-linear and as people say, probably a bit tougher than Surface Tension (which has plenty of powerful tanks and stuff that you learn can be quickly and easily confused).