The studio is known to be scammers. The side game you paid for was the only thing they planned on releasing from the start. 1st degree murder was a promise created to hook unsuspecting and impatient players who would pay for their short side game as they waited for the full release of the actual game they wanted to play. You are one of them.
Not only you, but everyone who has donated to their kickstarter has been lied to and scammed. This short side game is the only thing you'll ever get.