Let's wait and see if Crytek will manage to pull out a game without anything about aliens. I really liked Crysis, overall, but I must agree that the second half of the game was a little repetitive, and certainly more scripted than the first half. However Crysis was never meant to be a sandbox of chaotic unpredictable events, if I wanted that I would have installed some nice mods with S.T.A.L.K.E.R., which is an awesome game in its own right for that specific purpose (to prove that a game can be intense and fun without too much scripting, despite the inevitable bugs).
Although Crysis was short and more scripted than we all though it'd be, I think that it still managed to be a nice game along with nice graphics and sounds. I mean if I take a game like Half-Life 2 for example, which when released was quite a beautiful game, all I can think of is how dumb the A.I was (and still is), and how too scripted it was (just like a book), to the point where the whole thing was basically useless to play for a second or third time through, due to how much predictable it was. Sadly, Crytek decided to follow the scripts-driven story telling method from the second half of the game, and although it was quite fun, I personally don't want to play that part of the game again. However, I do play the first half of the game from time to time because there are still unpredictable moments (huge environment, free to skulk around, and the enemies will follow you, unlimited by any scripts to stay inside one part of a settlement for example).
We must consider one thing though, is that Crytek is new to the gaming scene. Yes they make good graphics, and yes, they can make good game-play (first half of Far Cry was awesome, same thing with Crysis), they just need to perhaps analyze more of what players want in FPS'es, and make sure not to make too much of what we've all seen before in other such games. They need to, maybe, add more variety in their games, more weapons, to make enemies more unique (I mean how many Trigens types were in Far Cry ? Three or four ? and how many in Crysis ? Three ? ... and let's not mention the Koreans, only two types, regular soldiers and Nanosuits ones, no special commandos, no rebels going with you and your cause, no prisoners of war willing to give some intel in the story line events, etc). And maybe more things I can't think of. Crytek are far from being bad developers, but so far their two games do have limitations and déjà-vue stuff in previous FPS'es.