After finishing these first steps I'm thinking about switching to Unity 3D as soon as v4.3 is released for native 2D support. Together with the excellent Tiled Editor I hope that's a good idea, let's see...
Some words to the combat system: My vision is to have a skirmish turn based and party based system that gives medieval fantasy RPGs a new twist. Imagine the system of Jagged Alliance 2 (e.g. environment interactions) is married with Heroes of Might and Magic 6 (e.g. initiative bar). Let's pick out two characteristics of the system so far:
1. Time: short.
The combat should be turn based but still fairly quick compared to similar system - for example due to renouncing health potions, healing spells or anything else which would restore combat abilities. It's all about eliminating enemy threads: The involved contrahents go down mostly after two or three hits and fighting against more than one enemy is extremely hard. I'm also thinking about enemy parties who surrender. XP folks, don't worry - as the player won't get any experience points for the own party from combat at all it doesn't matter how the end of the combat is achieved. The reward (besides experience points) will be paid when FINISHING quests, which have not to be solved by combat at all.
All in all the goal is to keep the overall time for one combat low to encourage the player to retry a combat in case it's lost. A fairly low random element should also support this idea.
2. Space: important.
My personal interpretation of medieval fighting is that it's all about distance. I'm not only thinking about crossbows and throwing knives but more importantly about the range of short clubs, two-handed swords and pole arms to name a few. With this perspective a two-handed sword could turn out useless when the enemy is in kissing range, without love but armed with a fine dagger. And don't feel all too safe inside a plate armor as for those there were also things invented. And one well positioned knight armed with a long lance standing in a narrow corridor is nearly impossible to overcome unless there is explicit long range gear available.
The idea is to have optimal fighting ranges for weapons on the one hand: In case the combatant is forced to fight with them at closer distances it becomes harder and somewhere along impossible. On the other hand it depends on the surroundings if there's enough space to bring heavy and long weapons on the battlefield - let's think about cramped dungeons, the need of swimming and diving... Once again - as with the concentrated time above - it's all about the LIMITS which make these combat situations interesting. Be sure that there won't be any backpacks holding big weapons or even heavy armor. And yes, most characters have (besides belts which could hold smaller weapons) not more than two hands.
At the end there are of course some good reasons why we haven't seen many (or any) RPGs featuring a full blown distance system in medieval turn based combat systems. It's really difficult to make the different ranges visible to the players without confusing them. The common movement systems (action points, hex grid, etc.) of skirmish games are also problematic: There has to be a good compromised scale between character graphics, graphical weapon lengths, possible distance classes and the dimensions of the room. Furthermore there might be also fighting between several people, e.g. two against one - and all three guys have different weapon lenghts... Or giant creatures who need more space on the battlefield, have long grabbing attacks, etc... Nevertheless I've cranked something out (in many hundred hours) that brings all these demands on one table with only little trade-off. More to be released about that soon.