For the details, Chema is correct: It is AIC; so the scroll vertically need to be in multiple of two steps, sprites move by 6 pixel laterally, there's no attribute conflicts because it's AIC so all the attributes are on the left side of the play field.Jonathan Bristow (also known as "Twilighte" in the little Oric World) has been responsible for some of the best pieces of software ever released for the Oric computers such as Zip'n Zap and Magnetix, but also some ports from other machines like Pulsoids, Stormlord, or Impossible Mission.
He unfortunately passed away in May 2013, and despite his efforts was not able to release some of the games he had started.
This is a short video showing one of the last prototypes of OType, which started as an horizontal shooter in the R-Type family (thus the name), before moving to a vertical scroller when he developed the AIC color system, this time inspired by the game SWIV (Silkworm IV), where the player could choose between sequences in planes, jeeps or as a commando soldier.
This demo version is relatively playable, the menus are partially working, including credits and highscores, and show that it would support various input methods and joystick interfaces.
Two players can play together, collision detection and hits are fullly functional, but sometimes trigger some crashes - which is why I limited the amount of shooting in the demo -.
Hope you like it, and who knows... maybe somebody will complete it one day?
(The music is from the C64 version of the 1942 game, which seemed fitting with the video environment).
Regarding the source codes, they are not lost, but there's some archiving/sorting to do/finish.
At least one thing helps us: Pulsoids and earlier games were 100% written either on the real hardware or using his own cross assembler which Jede had to write a special converter for because nobody could understand the syntax. Fortunately at some point he switched to XA so at least the code would not be alien to us.