I enjoyed both Raging Loop and Chaos;Head.
People rightfully mention how unpleasant the main character is in Chaos;Head, but you're not meant to like him. He's pathetic, paranoid and delusional. The atmosphere in Chaos;Head is thick and fantastic, you gradually become drawn into the conspiracy and some parts are genuinely unsettling. It's the first entry in the Science Adventure series and every subsequent entry (including Steins;Gate) builds upon the themes established in this game.If you read this, make sure you get the Committee of Zero improvement patch as the original translation is pretty awful.
Raging Loop is a wild ride where you're drawn into a game of werewolf where each night one of the villagers will be murdered and the following day theres a banishment ceremony where someone will be killed in an attempt to root out the werewolf. The thing is that you have the ability to 'loop' and travel back in time upon death. Sadly the ending leaves a lot to be desired, while I wouldn't say it ruins the entire story like I've seen some say, it is pretty lame. It's a shame because 99% of the story is great.