I am writing a space sim in Basic for Prizm.
So far it has spaceship controls (text mode, color) and preliminary mathematical model. The model is 2d -- all simulation is happening in the orbital plane. I believe it simplifies things quite a bit, both mathematically and user interface-wise, while leaving most interesting maneuvers available. Right now the model is for flat world with uniform gravity, so there is no orbits per se, only ballistic flights. To be replaced with model for one central planet, possibly extended to planet + satellites system + orbiting stations.

It is usable (with all its limitations) in its current form, but lacks readme, which i do not really need at this stage. If there is interest I could make a quick one and post the bundle as alpha.

I plan to supply several scenarios to complete one after another, possibly tied together into some coherent story. The action is going to happen on the Moon. The spaceships involved will be loosely based on Apollo program hardware.

Do you know of similar TI projects I can draw inspiration from?

sounds cool, why not do it in LuaZM?

Mostly because I develop it on calc, while reading a book "Fundamentals of astrodynamics".
Also, I believe there is a value in being able to change model and user interface on the fly.

Since today is the anniversary of the first manned spaceflight, I would like to release a beta of Sky -- my space flight simulator for Prizm.
http://www.casiopeia.net/forum/downloads.php?view=detail&df_id=104

It comes with 3 challenges/scenarios.
More to come as I implement more features in the model.

Chapter 1. Landing.
This story begins when your LM has just:
1) successfully separated from CSM,
2) performed descent orbit insertion,
3) reached orbit's periselene of 15 km,
4) decelerated to a complete stop.
You are 15 km above the surface.
1834 kg of fuel (less than a quarter of original amount) remains in your fuel tanks.
You need to land your LM with touchdown speed of less than 5 m/s.
Anything more than that means that the damage to a module is too great to complete the mission. More than 10 m/s would, likely, mean damage to the ascent stage that will prevent you from launching and you will be stranded on the surface until the oxygen and supplies run out.
(Warning: software does not check for max thrust. Do not specify fuel rates higher than 15 kg/s to keep thrust under realistic 44400 N)
Thrust direction controls and horizontal speed/distance indicator are disabled in this scenario to keep you focused on the main goal, successful landing.

Chapter 2. Escape.
The landing did not go as planned. One of the fuel tanks has developed a leak and lost all its fuel. The remaining fuel is not enough to reach the orbit. NASA dispatched a rescue LM, but due to rushed nature of a mission and no human at the controls, it landed 200 km away. With 1170 kg of fuel left, launch and land as close as possible to the rescue LM. More than 5 km miss means, that you are, probably, not going to make it. Also, since ascent stage is not designed for landing, the touchdown speed should be below 1 m/s with horizontal component less than 0.1 m/s.
(Warning: software does not check for max thrust. Do not specify fuel rates higher than 5.25 kg/s to keep thrust under realistic 16000 N)

Chapter 3. Orbit.
You found the rescue LM fully fueled and ready to launch. The original rescue plan requires you to establish circular orbit at 110 km altitude, where you will meet with the CSM that will take you home. Establish orbit as close to circular as you can at 110 km with periselene and aposelene within 110 km±100 m.
(Warning: software does not check for max thrust. Do not specify fuel rates higher than 5.25 kg/s to keep thrust under realistic 16000 N)

The sim gradually comes to shape. It simulates one body pretty good. It also tracks a second spacecraft in circular orbit so the first one can rendezvous and dock with it.

It also occured to me that Kerbal Space Program is, probably, more familiar name than Apollo program. So the KSP hardware and planet system might be more familiar to more users. So i might as well base the tutorial/storyline on the KSP, rather than Apollo. The benefit is that with KSP I am not restricted by actual historical events as with Apollo.

In your opinion, which path is more interesting
1) earth+moon+apollo hardware, closely follow actual missions plus several made up events for improved drama
2) KSP system and hardware, story completely unrestricted.

I like the historical feature of apollo, but KSP is interesting too, though not as dramatic.