Super Time Force

Introduction
The Impartiality achievement requres you to complete a level using 6 or more different players. There are 16 total characters in the game, 3 of which are playable from the start. You need to unlock at least 3 more characters to complete this achievement. Additional characters are unlocked by completing certain accomplishments or by finding them and rescuing them in certain levels (see the descriptions below for each character). Once you have 6 characters, you can complete this achievement by rewinding time 5 times and choosing a different character each time. Then, once you finish the level, the achievement will pop.

Unlocking Playable Characters
Below is a list of the 16 characters in the game and instructions on how to unlock them.

Available from the Start
1) Jean Rambois
2) Aimy McKillin
3) Shieldy Blockerson

Find and Rescue in a Level
4) Jef Leppard = Epoch 198X; Mission 1
5) Zackasaurus = Epoch 1,000,000 BC; Mission 1
6) Dolphin Lundgren = Epoch 9600 BC; Mission 2
7) Merlin = Epoch 673; Mission 1
8) Lou Don Jim = Epoch 3072; Mission 1
9) Melanie Gibson = Epoch 199X; Mission 2

Unlocked with Accomplishments
The following characters are unlocked by completing certain accomplishments, such as beating the story mode as well as collecting shards, glorbs, and lookers.

Shards are a small group of pink shapes found in each level floating around. They are collected by either jumping on them or shooting them with a projectile. There are 3 shards in each level.

Glorbs are small diamond shapes found in each level either floating around, being carried by an enemy, or released by an object after it explodes. They are collected by being touched by a player before they hit the ground. There are 10 shards in each level.

Lookers are similar to shards in appearance and are located at the end of every level. They are collected by being touched by a player, which will then transport the player back to the start of the level and give him 20 seconds to blaze through the level and re-touch the looker again before the 20 seconds expires.

10) Cleo = complete Epoch 199X; Mission 3
11) Commander Repeatski = complete all 6 epochs in the game
12) Squirty Harry = collect half of the shards in the game
13) Re-Bot = collect all of the shards in the game
14) Stash = collect half of the glorbs in the game
15) Da Vinci = collect all of the glorbs in the game
16) Looker = collect all of the lookers in the game

Changing Characters
Once you have a total of 6 playable characters, select a level. At the start of the level you are given a choice to select a character. Select one and then begin playing. Once playing, press the B button and then the Left Trigger to rewind time (i.e. take a "Time Out"). Then press the A button to open the character selection on-screen menu. Choose a different character than you just played with. Repeat that until all 6 characters have been called into the game, then complete the level as normal before the time expires or before you run out of Time Outs. The Impartiality achievement will then pop.