This is the list of things that still have to do done to the engine to make the single player version complete. After that, then the full multiplayer version is required to be developed using the same code base.
1. There is very little player creation code. More is required.
2. There are no spells, or similar area affect items/weapons/magic. This has not been developed at all, and will probably require a great deal of work and integration between items and map tiles.
3. The area editor needs a lot of work done to it.
4. The line of sight code is still to be finished. A shadow/fog-of-war effect and layering is being developed, but going slowly.