Serraxor wrote:Isn't this typical of like 90% of shooting games? The only 2P combined score shmup I can think of that I've played is Ai Cho Aniki

Yes, but Kokuga isn't a typical game. There's a heavy cooperative multiplayer focus, from the multiple paths in many stages to the card distribution relative to the number of enemies to the area-of-effect bonus for using support cards near your friends. It totally makes sense to track combined scores that reflect how well you've strategized as a team and made the most of everyone's multipliers.
And I basically agree with superstarsiro about scoring. To get a high score you need to
1) get every 10,000pt gatekeeper bonus
2) use every x2, x3, and x4 weapon to the fullest
3) defeat the boss, because if you don't complete the stage your score is 0
Just to post a score for the harder stages/difficulties many players will have to save their cards to survive the boss, while better players will be able to spend more cards to score during the stage and risk defeating the boss while underpowered, so there is a big skill/score gap there alone.
For players that can consistently do the above and are looking to fine-tune optimization, luck can start to become an issue, though it seems difficult to analyze. For example, in Stage A I'm pretty sure you need to score off that long row of turrets after the first gatekeeper. If you use Power Up combined with something like Dual Cannon you can take most of them out, but if you can't get Power Up to appear prior to the second gatekeeper (because your hand entirely consists of 2x/3x/4x weapons with nothing but the turrets to spend them on), then you're forced to destroy more of the turrets manually. (My best on Stage A Ultimate is 217,800 -- anyone score higher and approach those turrets differently?)
Incidentally, co-op would also make luck less significant if co-op scores were tracked.
Oh, and I'll make a high score thread if there's enough interest. I just didn't think of it because hardly anyone seems to be playing this game and there's no game-wide scores so everything would be spread thinly across... 51 leaderboards.