This is a hard-science fiction "Asteroids" game.

You are a hard working BelterRinga trying to make a profit by mining Saturn's A-Ring.

The game offers many viable playing styles. Watch the temperature of your nuclear reactor, or don't. Take it slow, or risk the occasional crash. After all, you didn't really need the front left thruster. You can compensate manually, just turn off the autopilot. It was aiming your mass driver slightly left anyway, ever since the barrel became misaligned. Or forget about the mass driver, you have enough cargo space to bring the rocks back whole. Or ignore the rocks and explore to find something (or someone?) lucrative. Maybe pirates. Or an escape pod. When you bring back an escape pod they always pay the reward, they don't ask why you found it.

Also has a demo available. Its the full game but without saving functionality.

If you know your way around memory editing tools you can easily skip into the late game.

I've been meaning to try this, but it seems like the kind of game where you need 5-10 hours to get into it and then you can play for hundreds of hours.

I've had it for ages. Grab the demo if you're not too sure. If you like physics based spacey games, this scratches quite a lot of itches.

Demo also has full mod support!