SEUM: Speedrunners from Hell is an AMAZING indie platformer, Quake-like video game (but without the guns 'n' stuff). Basically it's REALLY, REALLY COOL! So go buy it, it's around $25 on Steam!
These are not necessarily all the secrets in the game, this page displays only the ones that I found myself.
|Image||Level||Scanned string / URL||Redirect|
|5 - Fall Through||N/A||N/A|
|57 - Firewall||N/A||N/A|
|22 - The Wall||N/A||N/A|
|12 - Prison Escape||N/A||N/A|
|3 - Firestarter||bit.ly/SEUMfirestarter||youtube.com/watch?v=wmin5WkOuPw|
|12 - Prison Escape||bit.ly/SEUMPrisonEscape||youtube.com/watch?v=MbsuAbTTsV8|
|43 - High Power||bit.ly/SEUMHighPower||youtube.com/watch?v=Nnjh-zp6pP4|
|60 - Set Sails||bit.ly/SEUMSetSails||youtube.com/watch?v=ta-Z_psXODw|
|64 - Disco||bit.ly/SEUMDisco||youtube.com/watch?v=TY9_iLo4fSc|
|66 - Spider||Hello Croteam!||N/A|
|70 - Lamb on the Spit||bit.ly/SEUMLambOnTheSpit||youtube.com/watch?v=etwtK9Q490M|
|72 - Horse Race||bit.ly/SEUM-Horse||youtube.com/watch?v=vkevqPuDvqw|
|75 - Jump of Death||bit.ly/SEUMEmu||i.imgur.com/vIhecND.gif|
|80 - Broadsword||bit.ly/SEUMBroadsword||youtube.com/watch?v=LzmH7wf9zOU|
|83 - ???||bit.ly/SEUMToilette||youtube.com/watch?v=JSUIQgEVDM4|
I believe there is another secret in level 48 - Comb, but I can't find a way to get to it. There are some eye-catching platforms on this side. I think you need to jump from the platform and around the wall when it reaches the end portal, but I might be wrong.