UGO: What challenges are inherent in sticking closely to the source material (the latest 3rd Edition rules)?

TC: D&D was designed for paper-and-pencil play, so many of the rules tend to be a little awkward for a CRPG, especially the ones that require constant input from the player. For example, having to specify a dodge target every round is fun in PnP, but tedious in a computer game. Similarly, having the computer stop the game every time a potential attack of opportunity arises to ask if the player wants to take advantage of it was, quite frankly, annoying. So we had to find a way to implement such rules in a way that was close to the spirit of the PnP game but still fun and exciting for a computer game. Trust me, this led to MANY discussions (and some arguments) over the best way to handle this disparity. But the result was a computer game that is faithful to the rules and very fun to play in its own right.