I'm glad you mentioned that! I've just made some adjustments to the difficulty. After some research, I discovered that the Galaxians stage in the arcade version of GORF starts out pretty mellow, with just two Galaxians from the lower ranks attacking at any given time (the Galaxian bosses seem to move independently of the yellow and blue rows and attack whenever they please). I changed the code a bit to keep the number of attackers low in the first couple of ranks, but that number rises as the game progresses. There was also a bug in the code that made the CPU lose count of the number of attacking Galaxians, resulting in huge swarms that were nearly impossible to survive. That has since been fixed.
I've also reduced the number of enemies in the Space Warp stage, from sixteen in the first rank and twenty in subsequent ranks to the arcade version's twelve and sixteen. This and the faster ships make this stage run much more briskly than before, which is a plus because confidentially speaking... uh, I always hated that stage.
As to your question, yes, GORF is a pretty tough nut to crack in arcades. Typically, I can only reach Space Captain or Space Colonel (2nd and 3rd ranks respectively) with the standard allotment of three lives. The difficulty level of the GameBoy Advance game may be just a touch higher than that, even with the improvements... I suspect the cramped screen in the Space Warp stage may have something to do with that. I've made some changes to the game to compensate for the smaller screen, though. The Galaxians drop huge blankets of bullets in the arcade version of GORF, especially in the later stages, but I've limited them to a total of five at any given time. There are never more than five enemy projectiles onscreen at once; five bullets, five fireballs, or what have you. The lone exception are the lasers, although those are tile-based and drawn differently from the rest of the sprite-based projectiles.
Anyway, I'm babbling. In reference to your question, Cafeman, this is not an emulation of the arcade game, but a conversion, coded by hand. The audio and some of the graphics were taken directly from the arcade game, but I had to draw most of the graphics myself, making miniature versions that will fit on the GameBoy Advance's smaller screen. The resolution of the GameBoy Advance actually isn't much different from the arcade game if you flip the system on its side, but it's been my experience that "tate" modes don't work particularly well on the GameBoy Advance, and redesigning the game for that orientation would have been monstrously hard. I decided instead to make a sidebar and put status information inside it.
All right gang, here comes the latest beta! This time most of the sound effects are incorporated. All I'm missing are the digitized voices, and I haven't figured out how to make those work with all the other sound samples playing. Chances are, I'll have to move some sound effects (explosions, etc.) to the GameBoy Advance's sound channels and dedicate one of the wave sound commands (PLAYSOUND, PLAYMUSIC) exclusively to voice. Either that or I'll have to create a counter variable that prevents other sounds from being played as long as the Gorfian robot is talking.
Anyway, enjoy! Keep those comments coming, too! I want this to be as good as I possibly can make it!