KNOWN BUGS:
+ ootw: pool monster grabs you a edge of pool (glitch)
+ intro: there's still a bit of a pause when the elevator door finishes opening

TODO:

movement -- note these are hard due to limitations of the Apple II keyboard
+ running: Missing one running frame
+ ability to jump
+ ability to kick while crouching
+ ability to shoot

sprites_to_draw:
+ physicist jumping
+ physicist swimming
+ physicist getting out of pool
+ beast tripping
+ physicist holding gun
+ physicist shot

pool:
+ background of beast moving off

cavern:
+ slugs on ceiling drop
+ background of beast moving off

underwater:
+ add arrival-underwater scene
+ ability to swim

beast:
+ add beast death cutscene
+ add beast tripping

rope_room:
+ ability to swing on rope in rope room

cutscenes:
+ death by beast
+ aliens shooting beast
+ aliens shooting physicist

Level/Checkpoint #2:
+ Intro movie
+ Swing in the cage
+ Ability to pick up gun, with all that entails