In no particular order:

Secret / semi-secret variables

Secret functions

Global variables

Unicode support for the console

Blockchain integration

Closures instead of a quoted string in menus

GUI that looks for verbs

More sophisticated passage of time

GUI that runs in realtime

The Graphics Engine

Little game demos:

The monopoly game (Errands where you pass thru land owned by others with voronoi diagram)

The Spectra game

Heroes of Rock,Paper,Scissors

Come up with a plan for 'redirect'.

Modify World::scan_near to not allocate any memory, so it can be accessed as a 'getter' in the DrivenEngine.

probes should never modify the state of the world. Currently, there is no protection to guarantee this, except for something in lpxclient where it does a snapshot and rollback before and after the probe. We should come up with a more comprehensive mechanism.

### []()Questionable Design Choices

When we delete a tangible, we currently leave the LUA_TT_TANGIBLE flag on the table, and we leave the metatable in place with the tangible ID in it. Is this the right thing to do? Should we turn it into a truly blank normal table?

### []()Hard Problems without Solutions

**Using Multi-Core CPUs**: We want to do difference transmission in parallel (one thread per connected client). This may be possible because each synchronous model is a separate lua interpreter. However, the master world model is shared. It may be possible to access it in a read-only manner in multiple threads.

**Nonsortable Keys:** what to do about table keys that are other tables, closures, or coroutines?

**Collision Detection**: In the old engine, people could walk through walls. I don't know if that is okay in 2020. But the separation of world-model and graphics engine makes this hard.

**Dealing with Infinite Loops:** if the script goes into an infinite loop, there's no easy way to deal with that. The lua interpreter does have hooks where you theoretically could count cycles.

**Module-Level Locals:** module-level locals are useful to store constants. However, when they're used as variables, they create pseudoglobal state that gets reset every time you edit a source file, and which is unfindable by the difference transmitter.
