Rockman/Megaman X8 is brutal starting on hard mode. A new game plus isn't so bad but starting on hard mode means no chips(upgrades) and no metals(money). Easy mode is mockery due to starting off with a good portion of upgrades with all 3 life plus chips from the start. You can't get all the upgrades but you don't need them. The bosses don't even use their ultimate attack. Downside is no true final boss/real ending and no Ultimate Armor X, Black Zero, and White Axl.
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Medium you only have 5 lifes, you can get all upgrades, true ending, bosses use their ultimate attacks, you can get Alia, Layer, and Palette as well as Ultimate Armor X, Black Zero and the Sigma Blade, and White Axl.
Hard is chaos. 3 lifes. All enemies are buffed up. Bosses get serious when losing 25% of health and use their ultimate attacks after 50%(also multiple times as well if not killed.) Vava/Vile even makes the last level hell by making you go solo for most of the last level. Health is 10% less and you take more damage.
.hack, pokemon, and kingdom hearts has the best music of any games.