I'll admit I only tried retreating to heal once, but as a result I lost because I ran out of time, so I'm not sure how viable a strategy that is.
Anyways, different question. Is it just me or do skill points only charge up to 1 if you are logged off? Unless I somehow spent skill points without noticing, when I logged on this morning after being off all night I only had a single skill point to spend when I remembered to check.
(The other possibility, which isn't quite so lame, is upgrading the research academy zero's out all your skill points, and/or you don't start regaining skill points until you accept the upgrade. I did start an upgrade before going to sleep, which was obviously finished hours before I woke.)