Some of the principles people have tossed in from a past thread are:
balance
psychology of fun
building/triggering emotions
level design
emergent game play (what is that anyway?)
building complexity
design modification (perhaps this is simply part of iteration)
Is there a core group of principles in this stuff?
balance - this speak to the concept of difficulty. a game which is too easy or difficult is not fun.
level design is specific to level based games. and like interior design is largely a matter of opinion.
emergent play is when basic rules of the game combine to produce complex, unanticipated, beneficial results.
"attack equal or smaller within 50 feet" + "move to owner if far" makes my pet dire wolf chase small critters and birds just like real dog - and that was totally unplanned.
building emotional momentum really is only related to storylines in games. not all games are storyline based.
possible core principles:
balance and perceived fair play. all games should have this.
fun - all games should be fun. note that one person's definition of fun differs from the next. what you consider fun, others may not, and vice versa.
pacing - one should not progress too slowly or quickly though the game. a slow pace is boring. too fast a pace and you run out of content too quickly. you may also become too powerful too quickly, throwing off game balance, especially in later stages of the game.
not a whole lot else comes to mind offhand. and i have 6 years experience as a table top D&D DM, and 27 years experience as a PC game developer.
Valrus' posting above sums up the situation pretty accurately.