I liked the concept quite a bit, although I will agree that the gameplay changes take a little while to kick in. I though the controls were tight and the game was fun enough (although I may be hindered by the fact I played on my own haha). That said, I'd love it if you tweaked the ball physics a little, because I found it rather easy to make it just bounce in a straight line, which is not exactly fun (an element of randomization to the bounce might do the trick here?) Finally, a bit of a pause or some other transitional element when the styles switch would be great to get the players prepared for having a new rule set. Overall, neat idea and good work on the execution!

Very interesting twist on Pong!

Wow. Surprizingly!

I liked the evolving rule style, though it took quite a long time for it to kick in. I'm not sure is it timer or score based? The graphics are simple but effective. The concept plays well into the theme. Sometimes the paddles and the score go off the  edge of the screen.

This is not tennis >:[ and here's why!

Visual

The game has a simple artstyle, but it works incredibly well!

Audio

Great sounds, but maybe it misses something when there is a change in gameplay :)

Tutorials

Unfortunately nothing to tell the player how to move. Would've helped me to see it was a two-players game.

Gameplay

I like the non-necessarily mirrored gameplay between the two players, and the fact that it's not only a graphical change but a gameplay change. The only bad point I can see is that it's the same order for both players.

Fun

I had fun playing against myself, it must be even better with a friend!

Bugs

There is a sound bug when the ball is against the ceiling or the floor, or just if you move with the ball, it will spam the boing sound. 

If I'm right, the ball teleports above you if you crush it down while it's going vertically. But that's not really a bug, just weird.

Theme

Yep, it's in the theme :)

Interesting and unexpected idea! Nice works. ^_^

Okay, I got surprise there. Good job. But the ball is likely to get stuck or bug. 

I enjoyed the surprise of the game, but I quickly got the ball stuck bouncing vertically. Nice job!

Pretty cool, nice surprise. 

Thought the enemy AI was broken. Only to realize that I need play with myself :)

Cool concept for the theme! Good job.

Love the surprise mechanic!

Wow, took me a second. Nice one!

It took me way too long to realise the surprise, I'm a big dumb but it sure got me!