I played Pink, a web browser game by Bart Bonte. It is comprised of 25 levels, each with a unique, self-contained puzzle centered around performing some task to make the screen pink.
Although each level is different, the core mechanics remain the same, and are straightforward such that the game needs no detailed instructions or learning curve; you simply use your cursor to click, drag, and move objects. Puzzles range from moving tiles to slide a box out of a maze-like configuration to needing to recognize that you can hang a flamingo from the number“8” to pull down the top of the screen. 
In general, the simplicity of the mechanics makes the experience feel streamlined—which, for the majority of levels, it is. Some of the puzzles are solvable in just a few seconds or quick movement; others, even if the task itself is clear, take a bit longer—but primarily because of the thought that goes in prior to interacting with the puzzle as opposed to a long duration executing it.
Another strength of Pink is its hint system. A tiered hint system (where you can click a lightbulb in the corner of the screen for hint #1, then hint #2, and so forth where applicable) gives quick insights into approaching the current puzzle, and the last hint for any level essentially spoon feeds the solution. The nuanced and liberal hints congruently align with, again, those straightforward mechanics—the game wants to be your friend, rather than hold the player back in frustration.
Other satisfying design decisions include the sound effects, which are both helpful (such as understanding that an object cannot move through a barrier) and rewarding (you’ll keep chasing that iconic noise granted upon passing a level). I might consider trying to add a bit more variety in the puzzles (there were two that are very similar in aligning squares with individual letters over a grid, for example), which could also expand upon the types of fun—perhaps a timing exercise would expand the challenge, for example. Regardless, the linear level design creates a desire to chase discovery, there is gratifying difficulty in the best moments, and the workings of the game make for a smooth gameplay experience.
