I've had like a 30 min discussion with chatGPT to understand how Truebit works. The way I see it, Truebit is like a computation oracle that helps scale ethereum and possibly other chains. Truebit is not a chain itself.
In short, Truebit allows people to compute transactions and smart contracts off chain using a single computer and then submit the solution via the oracle to get a reward. Other people can flag the result of the computation if they think it is incorrect and get a reward as well. So it works very similar to how any oracle is used to get real world data, like the weather for example, on chain. On top of this they use a smart algorithm to determine which results are the correct ones if two people submit competing results. Coinweb uses something similar call "Refereed Delegation of Computation" protocol (RDoC).
Truebit uses a network of smart contracts and its own ERC-20 token to operate on Ethereum. So it's a token, not a coin. Also, it's a series of smart contracts that operate on ethereum, not a chain itself.
I'm rating this solution 4 instead of 5 stars because I think Truebit falls in the layer 2 category, and there are far more advanced technologies emerging in this field. Oracles are not deterministic, which i believe is a big weakness. Oracles are like bridges, which are often hacked and have multiple points of failure. The way I understand it, zk proofs are deterministic and can therefore be much more secure. So I'd rather bet on that technology.
You can see my conversation with chatGPT in the screenshots to get a full understanding. Show Less