The game makes you load portions of each map you play through, with jarring black-screen transitions. Those in-level loading times were never required on the SNES, so its inexcusable to include them on the iPhone version.
The other major offense of the iOS version of MMX is the ability to purchase upgrades like all weapons or all health boosts with real money instead of making the player unlock it by completing the game the proper way. Way to cheapen the experience even more, Capcom.
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http://venturebeat.com/2011/12/22/mega-man-x-ios-iphone-fans-hate-it/#AQL1vW43oL12VWSv.99