Simple but effective mechanics that were nicely executed. And anyway, I'm a sucker for a game with a dog. Nice song loop, good feedback from the sound effects. The graphics made me nostalgic for early '90s games.
The sound balance could use some tweaking. All of the sounds & music start off a little bit loud. Even with the volume turned down, the loudest tones in the music are as loud as the sound effects. Everything happening together is a little overwhelming. In the visuals, some color differentiation between the impassable rubble at the bottom of the hills and the passable rubble strewn around on the ground would also be good.
Playing in browser, I had a weird moment in which the MC suddenly shot forward into a zombie, his voice line glitched out like a skipping record, and I died. I'm assuming it was a glitch, but it gave me a good laugh. That *also* reminds me of old '90s game.
Overall a solid entry! Great job!