The Half-Ball Hit And Russian Billiards

Part two of Mike Page's excellent half-ball hit youtube series introduces the concept that the path of the cue ball of a half-ball hit is not very sensitive to the exact point you hit the object ball. That is, you can aim the object ball within a range of about 20 degrees of angle and the object ball comes out within two degree accuracy. In Mike's example, he cuts the object ball in such way that the cue ball drops into the corner pocket and it seems that he does it with great accuracy. But as Mike explains, it's mostly because of the cue ball path is more or less the same, if you just manage to hit the object ball in a range that is pretty wide.

Now, readers outside of Finland or Russia are probably unaware of billiards variants called Russian Billiards or the slightly different game (popular in Finland) called Kaisa. Both are played on a pretty large table with rather large balls. But the main characteristic of the game is that the pockets in both Russian Billiards and Kaisa are extremely tight. Like few millimeters wider than the balls. Straight-in shots are hard on these tables, unless you've practiced a whole lot. If the object ball is on the rail couple of diamonds away from the pocket, the shot is practically impossible.

[1] License of the picture: GFDL and CC-BY-SA 2.5, 2.0 and 1.0. Author: Alexei Kouprianov. 

The Russian Billiards has different variants and I don't know how each of those work exactly, but I think it's called "American" or the free variation, where you get points for pocketing the cue ball too. You'd think that pocketing the cue ball is pretty hard with these balls and pockets and you'd be right. But if you look at a typical game of Russian Billiards by world's best players, you'll notice that they make it look pretty effortless. And pocketing the cue ball is very powerful shot in that game, because not only you get a point for it, but you also get a ball-in-hand and for most shots, you'd like to be straight-in to make sure you get the object ball in.

I believe that the reason that they manage to pocket the cue ball so accurately is the exact same that Mike Page describes in his video. The angle that the cue ball must come out of the hit is much narrower in this game, but it's still not that sensitive to the exact angle that the object ball goes to. It's certainly not always an exact half-ball hit, but I'd claim that it revolves around it.