How to get: Complete level 5 while playing on easy mode.

Ending: The fake Mr. X robot is defeated, but the Chief of Police is still missing and Axel is still framed. Mr. X himself is still out there. and can still be stopped by trying harder (in other words, playing on normal or hard mode).

How to get: If you're playing on normal/hard you can continue to level 6. During this level, you'll have to save the Chief of Police before he dies of the gas that appears when the timer runs out. To get this ending, you'll have to reach him after the gas kills. In his dying breath, the Chief will tell you to get to City Hall. From there, you'll play a completely different last level and have to fight Shiva as the final boss.

Ending: Although Mr. X's attempt at injecting crime through means of the police has been thwarted, it is only temporary. Mr. X is still out there, still planning to take over the world.

How to get: For this ending, you'll have to get to the Chief before the gas kills him. You can get to him by destroying the machines in the 2nd rooms on both the bottom and top floors of level 6. Once you save him, you'll now start the real last level and be able to face off against Mr. X. To get the bad ending, you must defeat the final robot after the 3 minute timer on the screen runs out.

Ending: Mr. X has been defeated, but you were unable to stop his bombs before they blew up. The city is now destroyed, and large amounts of time and effort will be required to rebuild it.

How to get: This ending requires you to not do the things I stated. If you want the canon and best ending, play on normal or hard, save the Chief before he dies, and destroy the final robot before the countdown finishes.

Ending: Mr. X is finally defeated and the bombs have been disarmed. The credits play and our heroes can be seen looking out into the sunset, reflecting on their perilous journey.

Hopefully this guide helped in getting all of the endings. If you feel that this guide can be improved in any way, please say so in the comments.