Glad to hear you're enjoying Code Name STEAM it's a really fun new game by IntSys and...
OMG you're playing Rondo of Swords.
I have a stat topic for that if you're interested.
http://www.rpgdl.com/forums/index.php/topic,6523.0.htmlGeneral thoughts on how to play optimally:
Mages suck in the beginning, but are basically your best source of damage late. Make sure you train a few.
Elmer and Selmer are traps. Make sure you get the bonus mission in Ch8 by saving all the townspeople so you can get Cotton. Cotton is the best mage unit in the game out of the box. Marie has to be babied to make her work but she's the best healer in the game if you can do it. If you go the awesome story route, you won't get to keep Marie, so consider training Igraine, but if you can get by with just Cotton until Ch17, you get Aegil the Laser Pope, who requires a little babying but not too much and makes a great in-your-face mage with decent healing. Arios is fine, but kind of a trap as he doesn't become super awesome until VERY late, though he's serviceable if you just want a basic mage. Yumiluna and Galahad are too late to bother with, honestly.
ZOC is the most important skill in the game, and you only need level 2 of it, anything after that is kinda useless. Only Margus and the main on one path (the awesome path) get it early enough to matter much, but you can certainly get some use out of any of the PCs who get it.
Archers are the best units in the game. They can move and attack at range in a single turn. Their only flaw is being stuck hitting only one target in a turn ever. Ansom is likely the only Archer you'll ever get. The other one is good but extremely late-game. If you can stand it, sending Ansom on his Tarot quest will make him stupid-powerful.
The next best fighter is Alhambra, and also a good candidate for sending on Tarot quests. She gets a lot of good skills and gets them early and her stupid-high movement range directly equates to hitting more targets per turn.
Rukia and Owl are complete traps, don't touch them.
The only other thing to look at is whether a fighter has good range and whether you want their Tarot quest skill as you can only get so many of those. Sasha is decent if you get her Tarot quest. Izuna is good for ST damage. Simon eventually gets ZOC and has great range. Kay is decent early, but you'll probably wanna drop him for Simon or Alhambra.
General priority is Ansom >> Margus > Alhambra > Cotton = Marie = Aegil > Serdic >>>>>> Everyone else (Arios > Simon > Igraine > Yumiluna > Izuna > Sasha > Kay > Shino) >>>> Late-joiners (Naji > Alicia > Al > Galahad) >>>>> absolutely useless (Selmer > Owl > Elmer >>>>>>> Rukia)
Seriously, never use Rukia. Her only use is buying and selling stuff. Note that you should only use Shino if you're gonna use Izuna, which means that Shino is basically useless until Ch19, four chapters after you get her, and requires that you fulfill the secret requirements to get Ch19 to recruit Izuna.
The only items that matter are Move+ items and DEFENSE. Defense from Items doubles as partial magic resistance in this game, with the magic stat being the other half of the magic defense equation, though generally just load on the Item Defense as it performs double-duty. This makes it more important than the Passive skills that boost Def and Mag.Def, so I'd focus on increasing Atk and Mag there first, assuming the PC has those passives. Obviously boost Movement and Regen before that though. If you're not sure what a passive skill does or when a unit gets what skill... consult a FAQ, you'll always be glad you did!
Promoting characters is really tough, you have to find their promotion items through quests and such and then send the character to get promoted AS SOON AS POSSIBLE. I highly suggest looking up how these things appear as it's quite complex and you will NOT manage to promote your whole chosen team if you aren't planning it out ASAP.
(Note: Not actually that complex, just the game tells you nothing so you have to keep track of how it works yourself. Much like EVERYTHING in this beautiful yet unpolished gem.)