Here is the full list of all 88 Out Zone achievements.
Crush the spirit of life out of the second boss in the common version
Eliminate the second boss in the common version without assistance
Turn the first boss in the common version into dust
Eliminate the first boss in the common version without assistance
Upgrade any weapon to the max
You have achieved your first of many losses to come
Upgrade your weapons one time
Play a hundred games
Get terminated a thousand times
Fire one million buillets of any kind
Defeat ten thousand enemies
Upgrade your weapons a thousand times
Turn the first boss in the game into dust
Crush the spirit of life out of the second boss
Return the third boss to its maker
Put the fourth boss six feet under
Turn the fifth boss into shards
Deal with the sixth boss
Complete a cycle
Eliminate the first boss without assistance
Eliminate the second boss without assistance
Eliminate the third boss without assistance
Eliminate the fourth boss without assistance
Eliminate the fifth boss without assistance
Eliminate the sixth boss without assistance
Complete the game without assistance
Turn the first boss in the hard version into dust
Crush the spirit of life out of the second boss in the hard version
Return the third boss in the hard version to its maker
Put the fourth boss six feet under in the hard version
Turn the fifth boss into shards in the hard version
Deal with the sixth boss in the hard version
Complete the hard version of the game
Eliminate the first boss in the hard version without assistance
Eliminate the second boss in the hard version without assistance
Eliminate the third boss in the hard version without assistance
Eliminate the fourth boss in the hard version without assistance
Eliminate the fifth boss in the hard version without assistance
Eliminate the sixth boss in the hard version without assistance
Turn the first boss into dust in co-op
Blow the second boss to smithereens in co-op
Blast the third boss to kingdom come in co-op
Unleash fatal fury onto the fourth boss in co-op
Bring death upon the fifth boss in co-op
Emerge victorious from the sixth boss battle in co-op
Complete the game in co-op
Turn the first boss into dust in co-op without assistance
Blow the second boss to smithereens in co-op without assistance
Blast the third boss to kingdom come in co-op without assistance
Unleash fatal fury onto the fourth boss in co-op without assistance
Bring death upon the fifth boss in co-op without assistance
Emerge victorious from the sixth boss battle in co-op without assistance
Complete the game in co-op without assistance
Turn the first boss in the hard version into dust in co-op
Crush the spirit of life out of the second boss in the hard version in co-op
Return the third boss in the hard version to its maker in co-op
Put the fourth boss six feet under in the hard version in co-op
Turn the fifth boss into shards in the hard version in co-op
Deal with the sixth boss in the hard version in co-op
Complete the hard version of the game in co-op
Eliminate the first boss in the hard co-op version without assistance
Eliminate the second boss in the hard co-op version without assistance
Eliminate the third boss in the hard co-op version without assistance
Eliminate the fourth boss in the hard co-op version without assistance
Eliminate the fifth boss in the hard co-op version without assistance
Eliminate the sixth boss in the hard co-op version without assistance
Complete the hard co-op version of the game without assistance
Complete the game using only one credit
Complete the game using only one credit without assistance
Complete the game using only one credit in the hard version
Complete the game using only one credit in the hard version without assistance
Complete the game in co-op using only one credit each
Complete the game in co-op using only one credit each without assistance
Complete the game in co-op hard using only one credit each
Complete the game in co-op hard using only one credit each without assistance
Return the third boss in the common version to its maker
Put the fourth boss six feet under in the common version
Turn the fifth boss into shards in the common version
Deal with the sixth boss in the common version
Complete the common version of the game
Eliminate the third boss in the common version without assistance
Eliminate the fourth boss in the common version without assistance
Eliminate the fifth boss in the common version without assistance
Eliminate the sixth boss in the common version without assistance
Complete the game using only one credit in the common version
Complete the game using only one credit in the common version without assistance