What's interesting about Boomshine is they way it both fits into and defies expectations about "the game," that is, the elements that (pace Wittgenstein) all games actually do share, that makes them, in esse, games.
It's a little one-click game in which a number of colored dots wander about the screen, in a Newtonian way, bouncing off the edge of the screen. Once each level, you may click anywhere; doing so creates a bubble that quickly blows up to a fixed size, and lasts in duration for a few seconds. During that duration, any dots that encounter the bubble likewise blow up into bubbles -- and any dots that encounter this bubble then likewise cause dots to bubble up as well. In principle, you can clear the screen through a chain-reaction of bubbles; in practice, this rarely happens.
In each level, you have a target number of dots you must "bubble up"; three out of fifteen total on-screen, say. Thus, you have a goal to strive for (an essential characteristic of the game). And you do interact with the game, also an essential characteristic, though your reaction is reduced to the bare possible minimum; each turn, you click once, and while the resulting chain reaction is a consequence of your one click, you have no agency beyond your single action.
Goal-directed interaction is, of course, essential to any game; Boomshine pushes at the boundaries of this, though, because your actual agency is almost wholly irrelevant. While you can anticipate that clicking on some places will cause failure, it's essentially impossible to predict where a click will cause success. Except at the lowest levels, there are too many on-screen moving objects for you to grasp the dynamics of the system in any meaningful fashion. In other words, if one of the other essential characteristics of the game is that players' choices must be meaningful, Boomshine defies this; your choice (your single choice) is in fact not meaningful, because the complexity of the system makes it impossible for any human brain to guess meaningfully at outcomes, beyond perhaps the first few seconds after the appearance of the first "bubble."
And yet because you do have that tiny bit of agency, your choice still seems meaningful -- an illusion, perhaps, but you can tell yourself that if only you had clicked somewhere else you would have succeeded -- a truth, but you have no ability to learn or strategize where that "somewhere else" might be. It's a bit like how people respond to gambling games; the slot machine roller almost turned over to a winning image, the roulette ball almost came up with your number, and even though your control over the system is completely non-existent, you have the illusory feeling that next time you may do better.
Underneath the start screen is a statistic provided by the developer that betrays the unmanageable nature of the game; only 3.97% of all level 12 games have been won. Having played the level several times, I believe it; it requires you to clear an unreasonably large number of dots, a high percentage of a very crowded screen. Treating the game statistically is right; there's no way to predict or control it as a player. Evidently you have a 4% chance of winning each time.
Like Roulette or the slots, therefore, Boomshine is a game that provides the illusion of agency without the actuality, and yet that illusion suffices to draw you to, to get you to play the level again -- until, perhaps, you realize how unwinnable level 12 is. Of course it helps that the sensorium Boomshine provides is pleasurable; the music is pleasant and soothing, the moving colored dots and the patterns make as they bubble up pleasing. From a game design perspective, there's a lesson to be learned here: sometimes the illusion of agency suffices. And also that prettiness counts, of course.