Not necessarily science fiction, I just have that RHPS song stuck in my head.
It occurs to me that there are 3 main types of combat actions in MMORPGs: Weapon, Unarmed, and Magical. The first two would be physical traits, possibly augmented by magic-based buffs, while magical combat moves are... well, "magical".
It it for this reason that I usually think of my "soft classes" as having 9 different splits between physical energy and magical energy. Stamina-power and Mana-power or SP/MP, basically. Imagine a mana bar divided into 10 even segments... the most physically inclined of the default race would have 1 blue block on their bar (mana for spells) and 9 gold blocks (stamina for fighting/running/jumping). While at the opposite end of the spectrum the most magically inclined would have 1 block stamina to their 9 blocks of mana. There would be 7 steps between them, a total of 9 options. I call these "soft" classes because what type of magic or skills the player wants to focus on isn't really dictated by your starting point. It would be unwise to make a character with onyl 1 bar of mana and then try to make a mage of him, but if you wanted to you could try. All of these have at least SOME Stamina, since as I said... jumping or running would use physical energy. (Yes, in hopes of reducing those annoying bouncing players.)
Until players choose to add points to their base stats each stamina block and mana block would have the same value. Stats could be adjusted each time a player's XP bar filled, adding a point either to base stats or to profession/armor-class/combat stats as a boost in those areas. Base stats can affect things like: total HP, value of each Stamina block, value of each Mana block (to increase stamina or mana pool).
- Although outwardly "level free" I do think there would have to be a cap to how many points a player can put in their Base Stats, a cap which falls short of the combined "maxed out" point for that group of stats. Not doing so means that all players would just max out everything in base stats, leaving little varyiation in the player base. Being able to only put in say... 80 points out of a possible say 100 means players need to consider what attributes are most useful to themselves. In that sense one could say there are "80 levels" but people needn't put their first 80 points into their base stats at all. Instead, they can choose to speed up development in their other skill areas if they feel those give more advantage at that time.
A non-base stat area people may find worth putting points into would be armor-class. Light, Medium, and Heavy armor, basically. A player more focused on aestetics than on PvP or PvE, say a crafter, may want to unlock the ability to wear all the ligh armor... or ALL the armor... and focus on aquiring clothing to build a unique looking character before getting into other areas of the game where maxed out HP and the like would be more important.
As to combat methods, having the weapons skills in the form of unlockable trees seems like it would give a focus for "advancement" in place of the usual levels. Having several starting weapons, some of which aid a player in unlocking subsequent weapons provides tangible rewards for practicing weapons skills.
"Unarmed" isn't quite the right word for how I would approach the other combat path, since each "fighting style" would also include some weapon moves that one could not learn unless you've built skills in the hand to hand area. Sort of like learning a style of kung fu, a mastery quest would have you learn speacialty weapon moves. I'd want ot shoot for 12 "styles" having each style have say 2 weapons it carries moves for, some overlap of weapons between styles would be fine imo.
Magic, I had reasoned out as using elemental-based magics. Each character can carry as many elements as they have blocks of MP on their Stamina-Mana bar. Fighter types at the extreme could only learn one "type" of magic, mage types could hold up to nine elements. Mage players could choose between putting "all their eggs in one basket" or diversifying, which would have an effect as to what spells they could employ. Each element has a "style" of magic... fire doing high damage with some damage over time, lightning able to do massive damage or flash "holy" healing (but may be a mana hog), wood element does healing over time, things of that nature.
I think from the start the game would encourage players, perhaps in the starter area or tutorial, to at least dabble in all three areas. If the game includes situations where you have to stow your weapons in your bag to execute a task, like carrying items too large for your bag, then having the ability to fight unarmed is important and useful.