Some things I have worked on

TI-Runner Editor, a level editor for a Loderunner-like game that I reverse engineered.  This sold a few copies in 1987 before the TI/99-4A went under.

The arcade game emulator MAME, for which I did some work on the Windows UI.

Meridian 59, the first 3D MMO.  I created this with my brother Chris in 1994, and it was published in 1996.

My master's thesis was implementing the two-phase commit for Thor, an object-oriented database, in Barbara Liskov's group at MIT in 1995.

I built some nice multiplayer networking libraries for the Sega Dreamcast that unfortunately never saw the light of day.

Star Wars: Starfighter, a million-selling space combat game for the Playstation 2 and Xbox (2001).  I wrote the graphics, animation and collision detection systems, and snuck in a multiplayer mode as an Easter egg.

Game Programming Gems, a series of books on game programming.  I contributed to the first 4 volumes and was the editor of Game Programming Gems 4.

Google Desktop (2004).

Google Maps.  I helped launch Maps in 2005.

Google Earth.  Engineering director in 2010. 

Google Maps for Mobile.  Engineering director in 2011.

Google Now.  I co-created Google Now and recruited and led the engineering team.  It launched in 2012.

Peakbagger, an Android app for tracking mountain climbs, which I wrote in 2014.  I released an iOS version in 2015.

I ran an analysis of U.S. terrain data and found 10 new county high points.  Here is a KML file with the full results.

I ran an analysis of global terrain data to compute the true isolation of every mountain in the world.  A description is here.

After mountain prominence researcher Edward Earl's death in 2015, I helped to restore his WinProm program to a usable state.  I later computed the prominence of every mountain in the world here, and wrote a journal article here.