The art is the highlight here and is absolutely gorgeous. You have a great talent for illustration and it's all put together on the screen in a way that feels very cleanly executed and visually appealing. The ecologically-minded concept around guiding a herd of penguins is adorable yet actually fairly challenging! The stages are short, but there's a lot of technique in corralling the penguins so that all of them make it to the end. The upgrades system helps replayability a lot. I found the variance in upgrades worked well, and appreciated the light progression system by locking in upgrades, so that successive playthroughs of the game were made a little easier each time. Movement speed and herd instinct seemed to work the best for me.
Not sure I have a lot of constructive feedback. As a simple browser action game with light upgrades that looks very pretty, this game executes what it set out to do. very well. Maybe a little more of a variety of dealing with birds could help: standing next to a bird to wait for a progress bar to accrue feels a little abstract rather than a mechanic where you directly fend them off.
Great work!