a jetpack would not be impossible to do in Cryengine2, though at the moment, it seems these attachments and vehicle-type things are not possible to any large extent in Blue Mars. Which is a shame, but I am guessing it's not forever.
Anyway, I've started to see what I can do by just prying apart Crysis Wars, to develop a better navigation system, as it's got the full support of the engine. The movement in CW is much more fluid, and it's giving me some interesting ideas just hacking on it.
"To begin with," said the Cat, "a dog's not mad. You grant that?"
"I suppose so," said Alice.
"Well, then," the Cat went on, "you see, a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."
"I call it purring, not growling," said Alice.
"Call it what you like," said the Cat.