Great entry! It's nice to see different things like multiplayer. I, like others initially just played against myself but that's a obviously pretty unfulfilling experience and it took a while to get an actual two player game but I finally did. I can't tell where the full meta goes, but I worry a little about being able to wall yourself in for a stale mate. Obviously a lame way to play, but that's where it feels like P2 can end up easily having to respond to P1's attacks.
Having some additional visual change for the destroyed mirror would have been good, something quick like dimming them/reduce alpha via modulate, or literally a new sprite with some glass shards would have better conveyed that mirror no longer reflects. As is, it seems more like it can't move and will just block the laser.
I really appreciated the tutorial screens, though comically took a minute to see the "next" button, I think I was expected it in the bottom right with a more obvious background.
Again, it's hard to extrapolate what it would be like playing dozens of matches but there were some fun surprises early on in how things played out. Good work, keep it up!