Pick some logic you'd like to see work (example: right clicking a door will toggle the door state) and just implement it. Stop by the IRC channel to chat and we can find more things for you to do, too.
A freely-licensed texture pack would be great, I faced this same problem when developing a different voxel-based game. There are plenty of texture packs available on Minecraft Forums or Curse but very few released under permissive licensing terms, or those that I could find were outdated.
So I made my own, feel free to use it or parts of it if you would like to: https://github.com/deathcap/ProgrammerArt - it is updated for and includes all items and blocks for Minecraft 1.8, available in "resource pack" (1.8-1.6), "texture pack" (1.5), and "stitch pack" (1.4 and earlier, prebuilt texture atlas) formats. It is not the greatest quality artwork I admit, but can serve as a decent placeholder, and best of all is released under CC-BY 4.0 so it can be freely used and distributed. Though if your contributor makes a better free texture pack I'll probably switch =) cheers
If you had an army of 100 developers, what tasks would you set them to do to improve TrueCraft?
- Building a client with OpenGL
- Implementing world logic (grass growth, door logic, etc)
- Improving terrain generation
It'd be really hard to take on 100 contributors at once, though. In my open source projects, I need time to figure out how each contributor writes code and what they like to work on so I can leverage them appropriately.
There is no support for redstone right now. When support is added, any machines that work on beta 1.7.3 and not on TrueCraft are considered bugs in TrueCraft.