I would want the white storm back as a stage, DOA6 needs an actual snow filled stage and it would be cool for it randomly have the snow storm version at specific times. And to make it a more difficult and darker stage to fight on and to make it unique, they could do as the old DOAs did and make any hit land as a counter hit slip stun to make defensive on this stage more important
If they brought back Great opera I would love for it to start normal but hitting maybe a lit torch will cause the whole place to be ablaze, or evene better yet, you'll get the ablaze version if sworn rivals like Helena and Christie fight here, that would be so cool! They could also add a few onlookers and NPCs so it doesn't feel as empty and maybe they can run frantically in the upper echelon porches as the flames worsen.
I would also want either the crash club from DOA4 or the Rayhouse stage mainly as a way to have an arena to play the old remixes including the bonus remixes from DOA6 deluxe edition on this stage. There could be dancers watching behind the barriers and maybe stuff like hood gangsters and drug and yakuza gang warlords watching and betting in the back and maybe a pole dancer in a section as money rains down everywhere and people can cheer on.
The suspension bridge I want since I loved the major height drop when you fell from the bridge. They could also make to where some of the wood planks on the bridge can get cracked and cause the victim to fall through to the bottom of the stage if you hit it twice like the floor on the Dragon temple stage in DOA5. The stage theme imo should be Ayane's Dimesnions theme since it suited the stage perfectly imo. Maybe it could take place at night or maybe in mid day and there could be Easter eggs like Ayane's flower kunai that she threw and missed at Kasumi in Dimensions.
Burai Zenin would be a good way to represent Gen Fu since its his stage and it would be awesome to have a rainy stormy thunder stage to add something new to the game and characters could already start fully soaked or even gradually as they fight since it would be raining hard. The floor would also be wet so there would be a constant slip stun for lows on counter hit too
Aerial gardens should DEFINITELY return since we all thought it was being added thanks to the Kasumi scene of her with the fireflies in DOA6. XD this stage in DOA6 could be basically like in DOA2U but to make it more nostalgic and probably even darker to match DOA6's darker tone, it could be set in the very early morning with an ominous mist fog and maybe even some black crows or vultures and a bit of decay since its been 2 years since anyone has fought here. I would envision it being more abandoned and desolate in DOA6
Finally a last stage I would want(sorry if I added alot. I'll stop here since I could name pretty much alot of stages people would like xD) is the genetic biolab stage from DOA2U. To make it more of a darker stage tho and to have some influences with DOATEC HK, they could make to where there's a hidden hazard that drops into a deeper much darker lab with dim fog like in DOATEC HK in DOA3 that does massive damage. The music could be something ominous and dark like the APO stage in DOA6 and to make it even more morbid like in the older games, they can use Kasumi clone models obscured with maybe a thicker green gel or even just make the clones lack sexual parts like nipples and genitals since they're clones and have them floating around unconscious like in DOA2U and if you hit the tubes they'll crack and move around and breaking them will cause that clone to slither out and lie lifeless on the metal flooring. That would be so awesome <3 They could also maybe use Kasumi @'s dimensions theme for the stage. And the floor could have a constant shock when you fall like it did in the older games.
That's pretty much the major ones id want, sorry if I went on a rant, I just love stage design and making stuff more serious xD
