Old Sport is a geometric sans-serif font. I created it as an experiment, based on a grid system and following two simple rules:

 

1. Every letter must be composed of a single, unbroken line.

2. All areas must be exactly 2 lines thick.

 

I also based the grid off of a square, which gives most of the letter equal dimensions along both axis. The result is a chunky font with unique curves and forms.