There are many online gamedev competitions/jams. You must create a game from scratch before the given deadline. That's a great way to learn and improve your skills. Some of my creations in jams are presented bellow.
This game was designed and implemented during the 72 hours of the jam of the 25th edition of Ludum Dare. It is an Action RPG in which you figth the evil witch that attacks your town. It has been made in collaboration with Josema and David Cámara Iglesias.
This game was designed and implemented during the month of November 2012 for the GitHub Game Off competition. You are a tree that have to pick up water and salt in order to grow according to your rules.
This game was designed and implemented during the 72 hours of the jam of the 23rd edition of Ludum Dare. It is a Shoot'em Up in which you will have to defeat evil muon. It has been made in collaboration with David Cámara Iglesias.
Project developed during the Global Game Jam 2012 in Madrid. It has been made in collaboration with David Fernández Huerta and Manuel Rosado García. It is not finished for obvious reasons, but it was extra challenging since I had never used Flash before this Jam.
My first complete game! It has ben made during the 48 hours of the 22nd edition of Ludum Dare. I could improve it (had extensive comments and suggestions), but I don't want to lose the purity of unpolished work (meh, just an excuse.)
The best way to learn game developing is practicing cloning classic games. The following games have allowed me learning new technologies and improving my gamedev skills.
Tetris clone programmed in C++ using SFML. Besides the row elimination from classical tetris, there is also three-in-line elimination.
Light's Out clone for Flash. It's the second test with AS3 and FlashPunk. A bit more serious than the first test.
Pong clone for Flash. First test with AS3 using FlashDevelop and the FlashPunk engine. Just a simple first contact with the Flash SDK workflow.
First 'serious' platformer with complex animations (well, at least more complex than in previous games.)
Arkanoid clone. I don't consider it complete because I would have loved to add more levels, design power-ups, and some enemies.