contrary to popular belief, the wiimote does not have a gyroscope in it. gyroscopes are devices commonly used to measure rotation, so this may come as a bit of a shock to you if you've played kororinpa or its sequel, which are entirely based around rotating the wiimote to tilt obstacle courses for a rolling marble. instead, the wiimote features a three-axis accelerometer, which tracks linear movement. imagine that these devices feature a small weight suspended by springs. when the device is moved in a direction, the acceleration will cause the weight to squash a spring in the direction it moves in while stretching a spring in the opposite direction. thus, by measuring the squash and stretch of these springs (or whatever equivalent is actually in the accelerometer you're using), you can detect linear movement in any given direction. if you want to prove to yourself that this technology drives the motion sensing in kororinpa, simply turn the tilt visualization on during a stage, place the wiimote on a flat surface, and push it from side to side. even though the wiimote isn't tilting at all, the tilt visualization will rock back and forth as if it were.

knowing this, the precision of the tilt sensing in kororinpa stumped me for quite a while until I stumbled upon this tidbit of information. the accelerometer in the wiimote measures acceleration in its rest frame, which is on Earth, where we are constantly experiencing a gravity force downwards into the planet's core. because everything we are surrounded by experiences this, the accelerometer, if it were in free fall and only affected by the Earth's gravity, would not register any movement at all. likewise, when the wiimote is sitting flat in your hand or resting on a table, it is being pushed up against gravity, and so it registers a constant acceleration upwards. kororinpa exploits this by constantly tracking which axes the upwards acceleration affects at any given time. for example, if the wiimote is at rest and there's still a constant acceleration in the positive X direction (that is, jutting out from the left side of the controller), then the player must have rolled the wiimote clockwise, and the game will tilt the current level clockwise as well. extremely clever and well-implemented for a japanese launch title!

the gameplay brilliance of this control scheme comes from the ability to freely tilt each level in any direction and thus alter its relative position to the marble, changing walls to floors and vice versa. in each level, the game requires the player to search out some number of orange diamonds before reaching an end goal. combined with the ability to freely tilt, each level places its collectable diamonds in spots that must be approached by transitioning the marble up walls and back onto floors without accidentally letting it fly into the void. the best applications of these let the player skip wide gaps and navigate complex 3D mazes by "altering gravity" as well as letting the ball purposefully free-fall before catching it onto a surface with a careful tilt.

of course, the resourcefulness of this control scheme naturally forces restrictions on what kinds of levels are feasible without causing the controller to go haywire. firstly, because the reference values for movement are calculated when the wiimote is right-side up, it is much less precise when completely upside-down, and thus no stages ever force you to completely turn the wiimote over. secondly, because the reference view for the player must be consistent, the game always displays in a fixed perspective slanted down at the marble. any section that requires the player to roll the ball towards themselves cannot actually show upcoming obstacles to the player, which necessitates frustrating trial-and-error in these sections thanks to the lack of line of sight. the map, which does not allow free-roam and is uncomfortable fixed to the marble as a center point, is not a great help either. the most disappointing expression of both of these restrictions is the final unlockable level, which seems like the ideal complex 3D maze mentioned in the previous paragraph at first glance yet shies from truly maximizing the mechanical potential because every single section can be tackled without fully flipping the orientation of the level.

fortunately basic execution tests on your fine motor skills and ability to control your tilting through tight corridors and wall-less ledges serves as a solid foundation for the majority of the levels. most levels in the main campaign are less exploratory and more akin to linear gauntlets, which helps alleviate frustration with the camera. while the designers have a decent grasp on how to design appropriate challenges around the limited controls and unique free-tilt mechanics, the later stages begin exhibiting an uncomfortable tendency to escalate difficulty by simply drawing out the length of the stages. often times the most difficult stages feel more like disjoint challenges glued together with no connecting throughline, or worse, copy-pasted segments obsessed with testing consistency. fun enough for one straight playthrough, but rather tedious when going for faster times. perhaps they should've chopped many of these stages into multiple smaller stages and driven up overall stage count.

kororinpa is a budget title that can be bested within a couple of hours, but to the developers' credit they padded out the experience in meaningful ways for those looking to invest more brainpower. for starters, new marbles with different handling characteristics and shapes are unlocked during the campaign, and experimenting with which marbles work best with which layouts and hazards helps diversify approaches when optimizing each level. to encourage this, the game offers a rank system, with extra-difficult bonus levels appearing as the player achieves more and more "gold trophy" times in levels. there are also emeralds tucked away in each level as collectables; the best of these illustrate routes for interesting skips or narrow alternate routes, while the worst merely require tossing one's self off an edge repeatedly until hitting the emerald off-screen. each set of collected emeralds unlocks another set of bonus levels, which veer more towards "shitpost-y" themes like castle exploration and slalom skiing. it's unfortunate that these two separate extrinsic motivation methods feel antithetical to each other, as going for the emeralds often jeopardizes a gold trophy time, and you're unable to recollect emeralds after collecting them the first time in case you wanted to try a route that both sets a record time and collects the emerald.

overall this game shines best when it leans into the strengths of its control scheme and lets you devise nasty flips and skips, gently tossing the marble around between different surfaces. I would have liked to have seen more variety in these surfaces, as many of the levels descend to mediocrity by keeping all of their surfaces flat with guard rails and each of the joints between walls and floors completely 90 degrees. the most interesting levels are those that play with sloping surfaces, especially when switching between different slopes very quickly. another good variation on this are levels that feature heavy curved edges where one can build up speed yet must avoid careening off from the downward force, such as the ufo bonus level or the downward jam in the dessert world. more levels that utilized these concepts would have kept me from viewing a decent chunk of the levels as nondescript; a major dampener in any puzzle action game. still impressed by it nonetheless.