Unlockable difficulties:
To unlock Expert difficulty, beat the game on Hard difficulty. To unlock Ultra difficulty, beat the game on Expert difficulty.
Weapon upgrades:
Unlock the following weapon upgrades by performing the corresponding tasks:
WEAPON UPGRADE – HOW TO UNLOCK
Assault Rifle level 2 – Get from the box in Mission 5.
Assault Rifle level 3 – Beat the game on Ultra difficulty.
Grenades level 2 – Beat Missions 1, 2, and 3 on Normal difficulty with an “S” rank.
Grenades level 3 – Beat Missions 1 to 8 on Hard difficulty with an “S” rank.
Rocket Launcher level 2 – Beat Missions 9, 10, and 11 on Normal difficulty with an “S” rank.
Rocket Launcher level 3 – Beat Missions 1-12 on Ultra difficulty with an “S” rank.
Shotgun level 2 – Get from box in Mission 11.
Shotgun level 3 – Beat the game on Expert difficulty.
SMG level 2 – Get from the box in Mission 3.
SMG level 3 – Beat the game on Hard difficulty.
Whip level 2 – Beat Missions 5, 6, and 7 on the Normal difficulty with an “S” rank.
Whip level 3 – Beat Missions from 1-8 on Expert difficulty with an “S” rank.
Self Destructing Tank:
To set a tank to self destruct, press A. This can take out multiple enemies.
Rocket Launcher tip:
To target multiple enemies with the rocket launcher, hold B.