[Originally presented to acclaim at GDC 2009's Casual Games Summit, Nick Fortugno and Juan Gril's review of casual game design is an important look at the evolution of trends. Encompassing a wide variety of platforms, target audiences, and design concepts, the talk is an overview of the indie and casual games market, as well as a tool for creators to refer to in their own work.]

For the past two years, Nick Fortugno and I (Juan Gril) have worked in a session at GDC where we talk about the casual games that impressed us the most during the past year. We don't give Oscars away, as it's not a "best games of the year list".

Rather, it's a list of games we think are innovative, and we group them in trends. These trends are usually genres which are not stagnating (new games come out constantly with new design ideas in them), or are new to the market (a game or group of games which creates a new genre).

The following article is a transcript of our conversation in our session at GDC.

Intelligent Puzzle Trend

For the second year in a row we have found interesting puzzle games among casual games made for different platforms. It's a trend with a healthy stream of innovative games, and best of all is the trend with more radical innovation.

Juan: My pick for this year is Auditorium. Auditorium is a great game developed by Cipher Primer, an interactive design agency which just started developing video games.

Auditorium is a very simple looking game. You have volume meters, a ray of light, and directional markers. You have to move the directional markers, positioning them over the ray of light to make the light flow in a direction towards the volume meter. The volume meter will fill with the light and start playing the music.

As levels get more complex you'll have to deal with multiple volume meters (each one is one track of the composition). Color circles will change the colors of the rays of light to match the color of the volume meter, and portals and dividers will make things even more interesting.

Auditorium is a new take on music composition. It's a game that provides a very clear aural reward, with a clean and elegant interface.

Nick: My pick is World of Goo. The game was created by 2D Boy, a game design team born out of Carnegie Mellon University. The core mechanic for the majority of the game is simple: use goo bits to create a structure that you build towards a drain. When the goo structure reaches the drain, the remaining goo is sucked into the drain, and if the number of goo saved exceeds a threshold, the level is won.

It's a simple system, but it's developed out in continually surprising and engaging ways. The physics never get so complicated to become hardcore, but the introduction of new types of goo and new terrain means that the core experience remains fresh through dozens of levels.

For a game that is basically a set of physics puzzles, it goes well above and beyond in terms of visual and sound design. Each level has a unique whimsical aesthetic, and the variety from level to level is just astounding. Players are given multiple axes of success as well, and a set of OCD awards reward expert solutions to each board.

World of Goo shows the length to which a simple mechanic can be harnessed through smart level design and a creative approach to theme and style.

Other games worth checking out in this trend are:

• Jojo's Fashion Show: Great matching game based on fashion. Gamelab successfully used a topic so ephemeral in a game with a system of rules that fits to all tastes.
• Shift: A puzzle game by Armor Games about navigating a character to an exit, in which the player switches the character between the black and white parts of the board. It's a simple twist that creates many interesting levels.
• Neon Layers: A one button puzzle game by Ozzie Mercado, in which you have to direct a ball towards an exit by just switching lighted platforms on and off.
• In the Dog House: In this puzzle game made by Nitrome, your goal is to take the dog out of the house, by moving all the house parts around. It's a nice variation of the "car parking lot" types of games with a different theme.