WE ALREADY HAVE CSL (Counter-Strike Legacy) & RANDOMLY... this shows up. TF2 post-2008 and pre-2008. You were right. The SDK release would kind of create multiple versions of TF2 trying to look closer or better than 2007. The screenshots are from Enigma Studios responsible for TF2 Legacy.
Literally just TF2C under a different name. This is likely just a copy so don't trust it.
i really would not trust this project, like they used an already existing steam appid to skip the verification process, all shown on steam db's appid history