To be honest, I can only speak for the Geneforge series of games. (Those are the only ones I played to the end) Inventory might be a bit of a bother, but I thought that could be managed by a start menu system. Creations could be managed in party rooster system (the only one I can bring to mind atm is pokemon from way back in the day). As far as I remember, your character only has 4 active spells and 4 quick use items at a time, which could be toggled between when mapped to the traditional triangle square circle what not. Most spells were single target or could be done on what amounted to a grid based system. Admittedly moving around would require some serious changes, but I don't think that it'd be that much of a stretch.