Any type of keylock on the door usually is signaling that this area is more or less private and not everyone is welcome without permission. Outside doors usually have more serious locks installed, but if you need to add entry control to your room you may go with simpler solution – keypad operated door lock.
Simplest solution requires an Arduino, keypad and DC motor with belt pulley. Motor is controlled using H-bridge driver. When uses inputs correct code on keypad, motor unlocks door and keeps it open for 5 seconds and then locks again. The lock even has an audible output when lock king mechanism is activated. Speaker is also gonna be upgraded to knocking sensor in future. Other things like status LED and IR led for remote also may be added.