This cutesy puzzle game for the Game Boy stands out mostly because of the names of its main characters, Phillip and Marlowe, named after the famous detective created by Raymond Chandler and played on the screen by Humphrey Bogart. Except it has absolutely NOTHING to do with mysteries or film noir or much of anything, it's just really random.
I should mention that for those who have never played the game, but want to play it, it doesn't behave as a typical GB game. Depending on the emulator, the game screen will continually flash. That's not normal and an option needs to be checked so that is displays correctly. Something along the lines of merging the current and last frame.
Ah ha, that sounds like a (slightly) common graphical trick with original Game Boy games; some devs liked to "fake" additional shades of grey or transparency effects by flickering the screen at 30 hz. On original GBs with the blurrier, passive-matrix LCD screens, this would have the effect of producing a half-tone. On Pockets, Super Game Boys, Colors, and emulators, though, this produces a rather eye-straining flickering effect instead.
The option you're looking for to fix this, though, is generally called Interframe Blending. I think Visual Boy Advance refers to it as "motion blur."
That sounds about right. My guess is it's for transparency as there seem to be two layers to the screen. In my initial draft, I had a paragraph devoted to this, but I wasn't sure on the technical stuff and if it belonged in the article. The title screen also flashes, but that's for an entirely different and I think it's trippy as hell.
Yeah a graphic filter is one thing, what pennywise mentioned is different. I believe only this game and ZAS use that effect. There's another emulator (BGB I think?) that has the option to render the screen just as the other one is disappearing and thus, creating a blend that simulates the effect.
I've seen the flickering effect in other game boy games as well. At least one game used it (briefly) to create smoother fade-in/fade-out transitions between screens, and SPOT: The Video Game uses it at the end of a match to fade the game board into the background while it displays the winner.