Hello there! I recently played your game, and found all secrets in the levels I played. I only encountered a pretty big issue. On the end of the second-last level (Toxic Land), I am unable to end the level before dying to the ground. I think the trigger to end the level should be moved a bit closer to the final platform. I somehow managed to trigger the achievement for finishing the level, but I died and got sent to the start of the level again....

WHEN I REACH THE END OF TOXIC LAND INSTEAD OF APPEARING IN THE NEXT LEVEL I LOSE AND BEGIN FROM THE START

When you get past the wall that opens from the 'switch' the jump with the platform next to it isn't possible. The platform next to it kills you no matter where you jump, and the jump its self isn't possible to make.