What can a Magic Program do?

When you do a program, you have to ask yourself what you want from it - at least in Open Source, in commercial projects you tend to as others what they want from it...
my ambitions usually go very high, and it's not very different with Laterna Magica (that's how I named my project). I basically replace the question "What should it do?" with "What can it do?".
I want to list some features that a Magic program can provide:

• Rules Enforcement
  This is one of the two features that are the most interesting - and most difficult - features.
  Rules enforcement means that you have to teach the computer what a player may do. It's hard enough to teach a human to play Magic, and humans are at least intelligent.
  Implementing a rules system usually means to describe what the parts (cards, players, but also turns and combat) of the game are, what the possible moves and their outcomes are, and what moves are legal for a game state (the rules).
• Human vs Human
  Such a game is imaginable without rules enforcement. It's like paper magic, you make sure yourself that no one is cheating. examples for multiplayer Magic programs without rules enforcement are Apprentice and MagicWorkStation. This is relatively easy to implement, because you can skip the very huge rules enforcement part and can focus on a usable user interface and the network aspects. an upside to the user is that you can take shortcuts easily, a downside is that you may accidentally make illegal moves.
• Singleplayer Magic & AI
  Singleplayer games are harder, because it requires the computer not only to enforce the rules, but also to implement an Artificial Intelligence to make decisions itself, which is likely even harder than rules enforcement itself.
• Multiplayer games
  Games with more than two players are a challenge for several reasons: you're likely to do it over network, so you have to have a server which maintains game state, or connect every player with each other. Additionally, a user interface that shows three players is hard.
• Good User Interface
  "Last but not least": having a good interface is very important, because no matter how correct your rules implementation or AI is, in the end it's about playing a game, and that has to be fun after all. Maybe you're interested in This youtube video about the new MTGO interface. Wizards seems to have taken other Magic programs into account when designing this; some of the features seem similar to Incantus.
  I list it last here because it's far away from the other topics: my other four points are "low level" (although ideally the AI is also independent from the rest), and in a perfect world you could build a user interface on top of a program that was developed with no thought about it.