Nimbus Steam Achievements (17 total):

Goleyeath beaten ( Easy )
Cleared the final level on easy difficulty.

Goleyeath beaten ( Normal )
Cleared the final level on normal difficulty.

Time attack: World 1-9
Beat 14 seconds on World 1-9.

Time attack: World 2-7
Beat 30 seconds on World 2-7.

Time attack: World 3-2
Beat 20 seconds on World 3-2.

Time attack: World 2-11
Beat 27.5 seconds on World 2-11.

Time attack: World 3-5c
Beat 42 seconds on World 3-5c.

Treasure hunter
Collected all coins.

Cartographer ( Easy )
Cleared all levels on easy difficulty.

Cartographer ( Normal )
Cleared all levels on normal difficulty.

Time attack: World 4-4
Beat 20 seconds on World 4-4.

Time attack: World 3-12
Beat 16.5 seconds on World 3-12.

Time attack: World 4-7
Beat 45 seconds on World 4-7.

Time attack: World 5-2
Beat 30 seconds on World 5-2.

Scrapyard cleared
Cleared all levels at the scrapyard, on any difficulty.

Goleyeath beaten ( Hard )
Cleared the final level on hard difficulty.

Cartographer ( Hard )
Cleared all levels on hard difficulty
 

Nimbus Screenshots: