The timing window to get Marvelous steps in EXTREME US is the same as the arcade version of EXTREME. This also applies to EXTREME JP if you import.
"You're Not Here" - The song can be unlocked quickly if you defeat the AKIRA PREMIUM Challenge course in Challenge Mode.
"Wild Rush (From Nonstop Megamix)" - The Challenge remix for Wild Rush can be unlocked quickly if you defeat the THE FREEZER Challenge course in Challenge Mode.
"Trip Machine Survivor" - The song can be unlocked quickly if you can get Extra Stage. An Extra Stage is acquired by AAing a song on Heavy whose foot (or bar) rating is 8 or higher on your last stage with Event Mode deactivated.
Trip Machine Survivor will then be the Extra Stage and you're forced to play it no matter what with the 1.5x Scroll Speed and Reverse modifiers [REMEMBR: Reverse makes the arrows come from the top of the screen going towards the bottom]. At least get an A grade on the song to fully unlock it. After you unlock it, The legend of MAX takes over as the permanent Extra Stage.
"The legend of MAX" - The boss song of the game can be unlocked quickly if you MIRACULOUSLY beat it on Extra Stage. Get the Extra Stage (as stated above) and The legend of MAX is the only stage you'll only be able to play. The song has the 1.5x Speed Scroll and Reverse modifiers.
To unlock additional Nonstop courses, play each course in Nonstop mode and clear it once to add a new course. Repeating a cleared course does not count. After clearing 9 courses, you must clear 12 different courses to unlock the final course.
To unlock additional Challenge courses, clear the following number of different courses: 1, 2, 3, 6, 10, 14. The first 4 intervals unlock 3 new courses, the final two unlock one course (clearing 14 unlocks the 17th & final course).
To unlock Endless Mode, clear 200 songs in Game Mode (any difficulty level). Nonstop & Challenge Mode songs do not count.
To unlock the hidden songs in the game, play and clear the required number of songs in Game Mode (Songs cleared in Nonstop & Challenge Mode do not count unless otherwise indicated):
321 STARS-20 Songs
B4U (B4 ZA BEAT MIX)-65 Songs
CAN'T STOP FALLIN' IN LOVE (SPEED MIX)-50 Songs
DROP OUT (FROM NONSTOP MEGAMIX)-Pass 175 Songs
DROP THE BOMB-85 Songs
ECSTASY (midnight blue mix)-160 Songs
Frozen Ray (for EXTREME)-155 Songs
Funk Boogie-80 Songs
HIGHER (next morning mix)-110 Songs
KEEP ON MOVIN'-40 Songs
La Senorita-115 Songs
MAKE IT BETTER-25 Songs
ON THE JAZZ-70 Songs
PARANOiA MAX (DIRTY MIX)-130 Songs
Scorching Moon-5 Songs
The legend of MAX-190 Songs OR Get A on Extra Stage (you must already have Trip Machine Survivor unlocked for Extra Stage)
TRIP MACHINE-10 Songs
TRIP MACHINE Survivor-95 Songs OR Get A on Extra Stage (if not already unlocked)
TSUGARU (APPLE MIX)-125 Songs
V (for EXTREME)-170 Songs
WILD RUSH (FROM NONSTOP MEGAMIX)-145 Songs OR Pass "The Freezer" course in Challenge Mode
You're Not Here-35 Songs OR Pass "AKIRA premium" course in Challenge Mode
To unlock Mission Mode, clear 45 songs in Game Mode. Nonstop & Challenge Mode songs do not count.
A new dancing character is unlocked at the following intervals: 15 songs cleared, 30 songs cleared, 60 songs cleared, then every 15 songs cleared. The character awarded is random but is first a male character, then a female character, and so on.
On the Main Menu, use your 2P Controller and press the following: Right 4 Times, Up 3 Times, Square 1 Time, Left 2 Times, Down 3 Times, Square 2 Times, and Select 1 Time. Once you do this correctly, you will hear a noise confirming you have entered the code. Now "MEMORIES" has been unlocked.
First you must get mission mode from playing a set number of songs. In order to unlock everything you must pass EVERY mission in mission mode and then you will unlock everything.