The first game I played at GDC was Digital Bird Playground. It was on a big screen in the Mild Rumpus area so I collapsed into a beanbag and started guiding a seagull around a play area, hopping on and off a little yellow bicycle and throwing frogs through basketball hoops.
The reason I want to highlight Digital Bird Playground is that it does that wonderful thing of giving you enough tools and environmental props to prompt you and up to three local multiplayer friends/strangers/beanbag aficionados to make and play your own little scrappy games.
The best way I can think to describe that kind of environment is that it creates activity that reminds me of waves and water – there's a base level of exploration and running around because there's pleasure in the little interactions. Hopping on a bike makes a little bicycle bell ring, walking around causes the plants to sway and so on. Then you have these bigger swells of activity as you discover a kind of area marked out by railings and you all start putting worms into it. There's a cry of "Who put a frog in worm prison?" and then a little tussle as players try to throw frogs in faster then other players can remove them.
But someone has wandered off to investigate a ball and is trying to boot it into a goal. The action sloshes towards the little pitch and all four players are clustered round the ball, trying to work out which side they're on and how to make the goal counter on that side tick up.
But someone else has mounted their bike and now it's bike football. And now we're onto basketball. And now frog basketball. And now just following a frog around and then riding a bike into the water…
It's that; a lovely ebb and flow of play for half an hour on beanbags.
— Tom van den Boogaart (@TomBoogaart) February 15, 2016
[Disclosure: Alice is part of the Wild Rumpus which is the group which also puts on the Mild Rumpus at GDC. She was one of the other birds when I was playing Digital Bird Playground. I threw a frog at her to make her drop her basketball and then won at basketball. If she tells you that isn't what happened she is a liar.]