Primary purpose of `wasmi` is to be used with [parity](https://github.com/paritytech/parity) (ethereum-like contracts in wasm) and with [Polkadot](https://github.com/paritytech/polkadot). However, `wasmi` is designed to be as flexible as possible and might be suited well for other purposes.
At the moment, the API is rather low-level (especially, in the part related to host functions). But some high-level API is on the roadmap.
As `wasmi` contains a git submodule, you need to use `--recursive` for cloning or to checkout the submodule explicitly, otherwise the testing would fail.