Conny Carrot - Quest for Revenge  
A simple game but fun. The learning curve is perfect and it's got everything a game should have for something relatively simple. I would suggest expanding the game to make it full-length with bosses and cutscenes (though for a short game the intro and ending were perfect).

Revenge of the Ketchup 2: Tomato Paste  
The demo (first two levels) played well and there really isn't much to complain about. I look forward to the completed game.

Agent Manzana  
Plays fairly well though racing against time and collecting the apples just didn't do it for me, especially when there are so many apples in each level. Could be a great game with some additions and changes.

Becherdo  
The gameplay is essentially the main character going from screen to screen, in order, as you try to answer multiple-choice quiz questions. Still the game is pretty fun as the story is different and the game is professionally done. (Note: Despite the screenshots the game does have an English option.)

Zep's Dreamland  
I'd just like to agree with everyone else that this game is very worth playing, all the way through.

Icy Tower  
Fluid gameplay but it does get repetitive after a while as nothing changes once you've learned how to play. Despite that the game is well made and a fun way to waste a couple of hours.

Alex the Allegator 4  
Alex 4 is very professionally done and quite enjoyable. The map editor and the unlockable mini-game are nice bonus treats for those who like extras. Looks great. Sounds great. Plays great.

Anthem of Dread  
Great start and looks promising. It already has a comfortable feel to it but I would imagine that may change drastically over the course of development.