I played 3 games and I want to break down my opinions about them from 2 perspectives each. Designer/Programmer and Player.
Wizard-Wizard is mechanically fairly simple. The core mechanics of the game are left and right movement, single jump, and double jump. There are only 3 buttons necessary for control, left arrow or a, right arrow or d and up arrow OR w for jump. The player must collect a key then navigate to the exit to complete levels. Each level can be viewed as a puzzle to retrieve the key. It seems to me that there is a deterministic first order optimal path (a shortest path) to this game that would allow for a player to get the key and navigate to the exit fastest on each level. Player jump timing is also key to the understanding of how the levels were designed, blades were placed in such a way as to be challenging but not impossible.
From a player's perspective I think Wizard-Wizard is fun due to the nature of the level/puzzle design, and movement mechanics. Mastery of the mechanics made me able to get to level 29 in about 15 minutes. A colleague of mine had more trouble in this regard and as such didn't get quite as far. On a couple of levels the timing of when a player should jump is within a split second of a circular saw blade passing over, in this regard I could definitely see this game being frustrating to players unfamiliar with playing platformers due the precision of timing necessary for success. The game seemed far easier when using AD for movement and up arrow for jump.
The source of fun:
While looking at the Wizard-Wizard project and its source code it becomes obvious very quickly what a simple project it is. It is primarily art assets, with some simple scripts attached to objects to control their movement (such as saws, player movement, etc) and some checking scripts (a total of 4). Any of us could feasibly make a game like Wizard-Wizard. However the major challenge in designing a game like Wiz-Wiz is definitely level design, as making the game too easy, or too hard could happen without too much effort on the part of the developer.
Canabalt is a side scrolling runner/platformer where the player utilizes a single button to jump. The goal of the game being to time jumps properly. Properly timed jumps allow the player to make it from rooftop to rooftop, or not hit obstacles such as boxes which cause the player to lose momentum. Loss of momentum will cause a player to fall to their death.
From a player's perspective I found this game more frustrating than Wizard-Wizard. Making progress in this game could feel really negative being that I never saw a checkpoint (if any such thing existed) and the fact that I could keep all of my momentum up to a specific jump, which I would then proceed to fail to time, each time I approached it. This would cause me to fall to my demise.
Wizard-Wizard's obstacles could be more difficult to dodge due their placement than Canabalt, however Wizard-Wizard was more like a platformer. Wizard-Wizard was more forgiving than Canabalt however, double jump would allow a player to occasionally come back from a near fatal jump. On the opposite end, hitting a box wouldn't kill a player in Canabalt but would set the player up for failure when they would come to a building jump. It was almost like collecting momentum debt until the game asked the player to pay it off(at the jump).
Aesthetically, this observation seems to make Wizard-Wizard more fun.
Playing vs Observing::
While observing my colleague play Wizard-Wizard I thought the game would be very difficult, but after installing it myself, I realized that my natural bias toward platformer mechanics made me rather decent at the game. I didn't die for my first time until level 16. While playing, it was easier to notice how difficult a jump might be, that is, how timing was tied to the gameplay. While watching, it was easier to see what the overall thought process and strategy the game's designers had in mind. A jump that might look easy to a designer could be substantially more difficult as a player.
This is the only level::
A single level, I can't specify the controls exactly because the controls would often change as a result of completing the stage. When the player would hit the exit pipe, they would spawn at the beginning of the existing level, and would have a different mechanic of play, whether it be, don't step on the stripes, or click to move instead of arrow keys.
I found this game fun as a player, specifically because it challenged me to think about the environment in different ways despite it being rather static. It would however be easy to see how a player could find themselves frustrated in "This is the only level" one might find themselves frustrated after beating a few stages. The reasoning for this would be the fact that your controls change and you find yourself mashing everything to figure out how to move your elephant.