You won't wax poetic over this one, folks.
Crayon Physics Deluxe is in the libraries of scores of fiscally irresponsible gamers, having been included in a Humble Indie Bundle before the Humble Bundle service had bloomed into a full fledged shop. It was specifically included in HIB 3, which included the tremendous VVVVVV. It also included the decidedly less tremendous And Yet It Moves, a port of a WiIWare game perhaps best left in hits home mode, and Hammerfight, a shambling mound of east European physics based, mouse driven combat that only Dave Snyder could love. If not for my outright disdain for the latter, CPD would be my pick for HIB 3's real turd.
The game itself is a mouse driven puzzle game divided into a series of thematically linked challenges on a map. Each core problem is the same: navigate a small red ball to the immediate proximity of a golden star. This is done by using the cursor (or, in ports to mobile, your darn finger) to draw objects within each single screen level. The game starts with fairly rudimentary challenges, such as drawing a simple line to bridge a chasm for the ball. Eventually you are shown tools like pins (to attach new shapes to existing geometry) and ropes which become instrumental in solving some of the more clever puzzles near the game's conclusion.
I have two problems with the game, and they're massive. The first comes down to the underlying system of physics that governs how objects interact in levels. This breaks in so many different ways. When levels scale in complexity, the solutions to puzzles (which are mercifully freeform, though there are optimum paths to completion which may or may not be apparent) tend to become increasingly complex. This can lead to moments where the game becomes shockingly un-fun. For instance, a winning strategy near the end game tends to involve a sort of gravity winch: a rope tied to a container that carries the ball on one end, and a weight supported by a platform or pin on the other, with a fulcrum piece of geometry in the middle. Release the support for the weight, and the ball container is pulled by the rope to the star. In theory. The rope could also never really be pulled, or your weight may stick to a piece of geometry, or the ball container could be pulled over the target star by the force of the pull. You're then left to repeat the level, often iterating on the same solution until you've got things just right. I find this tedious as hell.
Other levels suffer from this sort of "bashing against the problem" gameplay. Some require you, for instance, to interact with large physics driven objects within the level. The worst of the lot are basically large, crude drawings of villainous people which must be painstakingly moved out of the way of the ball. I was finally able to accomplish one late game iteration of this problem by employing three separate winches, two levers, and a handful of straight up heavy object drops to dislodge the ball from the creature's belly. This also took about fifteen minutes, about half of which was just waiting for momentum to shift. It was awful. Even worse offenders are levels which require use of rockets, launched by striking them with some force, to propel the ball to stars throughout the level. One of these I never will complete; two stars were nestled behind a sun and a moon, with two rockets on ground. I probably spent half an hour attempting to fire a rocket in a meaningful path to either star, to no avail.
Ultimately, the physics-driven nature of the game and the tools provided to solve each problem lead to a fairly reductive solution that can work in most levels: use pins and rope to steadily scoop up and under the ball, lifting it to higher and higher levels of rope, until you reach whatever desired platform you wish. Akin to something like Scribblenauts, finding the most surefire solution can simultaneously be the most reliable and least interesting path to victory.
That dovetails nicely into my second complaint, which is the level progression. Completing each level unlocks one star. There are three optional challenges to each level, however, and completing these challenges unlocks a second star per level. The game teases you to engage with this mechanic by gating a level at 120 stars on the map.
Encouraging clever and skilled play is a fine thing. That said, I personally found this system lacking. The challenges per level are: completion by using one object, completion by not clicking the ball (which gently propels it forward or backward) or pins, and holy shit the last one is on the honor system. This all strikes me as either wildly difficult or laughably easy, and yet to not engage with these extra objectives is to ensure you will never see the full content of the game.
Ultimately, though, that's fine by me. During my hedonistic Humble Bundle period I wound up purchasing nearly 80 games through the service. I've been trying to winnow through them ever since, trying to complete each one in some vainglorious attempt to justify the money spent. I have forever had my fill of Crayon Physics Deluxe, and don't give one good goddamn what's behind the 120 star gate. Were it not for some of the puzzles being enjoyable and the relaxing (if not particularly stimulating) soundtrack, this would be kind of a disaster. As it is, it's a brief puzzler with decidedly mixed implementations of the features that define it.