A 2d Half-Life would probably not be very “groovy”. Compare Age of Empires: Age of Kings to any Age of Empires game on PC. Which is the more fun?
Then what would you rather play: Codename Gordon or Half-Life 2?
I’m not trying to discourage you, there just seems to be little point in making a whole new game with a whole new interface and slapping the Half-Life name on it. It would be like remaking Half-Life in ‘RTS’ form. It wouldn’t be the same or even very fun.