There are some older projects, dated back to 2014 which develop contracts in CLL, C-Like Language. What is this and is this still being developed/used?
CLL is both an acronym for "C-Like Language" and the name of an Ethereum high level language that eventually became Serpent. Vitalik described CLL as "the stripped-down-Python-like language in which you can write Namecoin in five lines of code" in this blog post from February 2014. It is no longer being developed or used.
It was one of the earliest incarnations of the Ethereum high level smart contract languages we use today. An example of an Ethereum C-Like Language is Mutan.