I never tried the PS2 one but Omega Factor is great because Treasure were.
I kinda understand that Tezuka's company weren't too keen on an action game as Astro himself prefers dialogue before fighting (kinda like Superman in a way) so he's more pacifist while Megaman goes into the fray in his games.
I do love Bombman's stage having spherical building in the background.
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I think these were shown in a Tezuka manga but I cannot find the right panel.
Also Bombman was really supposed to be called Bomberman but Namco said "no"?
I would've liked that kind of crossover myself.