Rust-Lightning, not Rusty's Lightning!
A full-featured but also flexible lightning implementation, in library form. This allows the user (you) to decide how they wish to use it instead of being a fully self-contained daemon. This means there is no built-in threading/execution environment and it's up to the user to figure out how best to make networking happen/timers fire/things get written to disk/keys get generated/etc. This makes it a good candidate for tight integration into an existing wallet instead of having a rather-separate lightning appendage to a wallet.