Thank you for your feedback! Did you try entering in a time value and then pressing "Start"? Without entering a time, the default behavior is for start and reset to be no-ops. I'll add a link to GitHub and add some usage docs soon.
Aha, I expected it to count up to 25.
Maybe it is just me, it was around 0500 in the morning when I tested it, but it probably wouldn't hurt to add a hint.
Ah, I see! I could see why that would be a more intuitive behavior (as it's more in line with the standard 25 minute Pomodoro). I added a link to the repo, and the README includes information about how to use it, but I will add some hints like you describe so that people visiting for the first time aren't caught unawares.