I suggest you try it to see the effect anyway, quite impressive. Try with dimahoo, which looks really "slim" on a horizontal screen, then rotate the screen and behold !
By the way most of the vertical games are shoot'em up that's right, but not all of them. I just added an option to be able to add -rol and -ror on the command line when using -gl to display games rotating on the left and on the right, which gives as non shoot'em up vertical games :
- pacman, all its clones, including miss pac man & cie.
- arkanoid 1, 2, & returns. About returns it's been broken for quite a few versions, I just noticed it yesterday while checking for this windows asm compatibility. It's fixed.
- block block, which I never played
- bomb jack twin
- Don Doko Don (platform)
- Donkey Kong (better with emudx graphics, which are broken with opengl blits in windows, too bad !)
- Drift Out
- Exciting hour / matmania which is one of the rare games I played a lot with my cousin in the arcades, back in the day, a wrestling game... !
- fantasia (!)
- frogger (same comment, better with emudx graphics)
- gal's panic
- Grand Cross Pinball
- Kiki Kai Kai / knight boy
- Liquid Kids
- Maze of Flott
- Mercs (although it's a commando like game, so shoot'em up but not in space !)
- Pengo
- us classic golf (not as good as the neogeo version)
But yes, the vast majority are shoo'em ups, some very good ones being vertical indeed !
And while testing yesterday, I finally understood why there was no progression in the dialog when loading a rom from internet archive : it's because of their server which doesn't send the size of the file before the download. So I added a workaround by taking the list of the files in an index file, and getting the sizes from there. It works, the progression works again, useful for such a slow download, at least it proves that it works and it's not frozen !