The playability is just great ressembles much of the original.
The effects are just great, you've chosen just the right ones here.
As an artist I have some more critical thoughts about the look of the game.
The monsters are good as they are. (not so critical... eh)
Jack's animation is a bit too simple while walking, if you'd put 2-3 frames into the animation that would made it great as well.
The interface is OK.
The photos as background just don't work for me. Very distracting (mixing photo and pixel art is not really good), at least for me. I understand the need, and even if the photos look great in themselves, they are not as good as a background. I can't stress it enough: for me.
Anyway it is a fine 90% from me and keep up the good work!
I still play Bombjack and other games on my Amstrad CPC6128 and sometimes on my CPC464. I even do the odd bit of programming in Locomotive Basic and Maxam 1.5 assembler.
The best Amstrad emulator on the PC seems to be Caprice32.