Atari Breakout - Google image search

So here's how the Ikaruga element worked: each player had three controls 'up', 'down', and 'change bat colour'. The bats could be either black or white, and so could the ball. If you tried to return a shot but your bat wasn't the same colour as the ball then you'd lose the point. The beauty of it was that if you were holding down the 'change colour' button when you returned the ball then the colour of the ball would change. So let's say you have two players who are getting into a heated rally both with white bats and a white ball. They're concentrating on trying to catch the other one with good shots rather than the colour when, suddenly, one player presses change colour to change their bat to black, then again to change it back to white, but they keep it held down. They return the next shot and now the ball is black. Their opponent has to change their bat colour quickly in response otherwise they'll lose the point. Pretty soon the mindgames set in - changing your bat colour twice but not holding down the button to trick your opponent into thinking the ball is going to change colour, or my personal favourite always changing the ball colour and then suddenly not doing so out of the blue. We could have made a fourth button for the change ball colour instead of doubling up the functionality of the change bat colour button, but the way it telegraphed possible intention was kinda cool. That was the Ikaruga dimension of the game.

There was another nifty element I remember too which was that the ball was returned faster the closer to the centre of the bat it was struck, or slower nearer the edges, with a few pixels of sweet spot in the exact centre which would give a mega shot.

It was one of those games you make quickly and then spend hours ahem "testing" multiplayer in between adding new features. It was really fun because of five main things to be thinking about while playing: simply returning the ball (!), having the right colour bat (the most basic Ikaruga element), putting tricky spin on the ball (made all the more fun by the rotation of red diameter line showing exactly how much spin you'd put on it), hitting near the centre to make a fast hard-to-return shot (with a satisfying "whoomph" sound and particle trail effect for the mega shots), and finally the cheeky ball colour switch mindgames.

I'll have to dig it up, check it all still works, and put it somewhere for people to download. Or at the very least make a youtube video to show how it works (on reflection, that would have probably been less effort than the above write up!). Cheers :)

As far as litigation is concerned, I would expect that bigger companies would tend to get sued over trademark issues. After all, isn't that where the money is at?