Easter Egg: In the newest version (as well as the HD), you get a super awesome third ending if you end Level 8 on the awesome X-4 and be sure to collect ALL the gems FIRST! You can also unlock a super awesome bonus title screen if you 100% the game!
Let's Play: By DeceasedCrab. It's also been LPed blind by a fine fellow from the Let's Play Forum. It's actually one of the most let's played freeware games of 2009.
Multiple Endings: A bad one at the end of X-7 if you don't have all the gems, where Zee Tee fails to rescue Nehema. But when you collect all of the gems and beat X-8, you get the Good Ending where Zee Tee and Nehema live Happily Ever After! The HD version even has an extra special ending where Zee Tee and Nehema are together in pure happiness forever and ever!
One-Hit-Point Wonder: You're a flower-resembling asterisk, so this is kind of a given. Don't worry though, you have infinite lives!
Sugar Bowl: Once again, look at the page image - that's the world your flower character will start his travels in! It gets even better as you go on!
Sweet Dreams Fuel: Nearly everything, but the first three or four levels, and possibly the eighth are certainly the most memorable!
Take That: The 'Metaphor for the Atomic Bomb' achievement takes a jab at another Mario-esque platformer with an added mechanic. The tone is evident from the icon for the achievement: Zee Tee and Nehema making the 'awesome' face.
Unwinnable by Mistake: Some level designs can lead to the player getting stuck in one place without being able to get out or die, and the level must be restarted. Some instances of this were corrected in later versions, but it's still possible to purposely enter a unwinnable state in some locations. Fortunately, you can quit the level and restart without losing any of the gems you've collected during that level!