TL;DR - Super Ricko's Islands is... acceptable. Full of underdeveloped or incomplete mechanics, as well as leftovers from the previous version. If you've got nothing better to do, you can play it, but don't go for completion, because it's impossible.
This is one of the few games I can think of which has vestigial game design - useless or broken remnants from a previous version of the game called Ricko's Island that was removed from Steam. All of the coins you earn aren't used for anything, but in the original game, you apparently could purchase abilities, extra jumps and air dashes, and perhaps other things. Additionally, the past version of the game also took inspiration from Super Mario Odyssey, giving the character the ability to take control of monsters, but this has been stripped out from [i]Super[/i] Ricko's Islands, [u]leaving some collectibles inaccessible in the new version, and mandating your own death to collect others.[/u] Still others don't seem to exist at all. For this reason, you shouldn't get too invested in completing the game.
You have the ability to jump, double jump, air dash, wall jump, run, and sprint. However, the controls are awkward, and aren't delivered in a proper tutorial at all. The most you get is a toggleable in-game UI display of literally every action you can perform, with unclear written instructions for each. It took me awhile before I understood how to perform a double-jump (in the game called an "air roll"), since it requires you to jump, air dash, then hold run and press jump, but only within a short time window following an air dash. It took me until the eighth world to realize there was a high jump you could only perform during a "super sprint," which itself is performed by holding both the run button and the dash button after dashing. The game will toggle your run or super sprint state off after each jump, even while you continue to hold the buttons for those, which makes some of the race challenges obnoxious.
The objective of the game is to collect cores, floating balls of light with bands orbiting around them. You have to collect an arbitrary amount of these to unlock each additional level. Of course, there's not any other reason to collect them, as there is no proper end to the game, and no reward other than additional gameplay.
There are 9 islands (though I've seen some say there's 10), all of them featuring relatively lazy level design, with just a height map, scattered cores, "supre" cores, checkpoints, enemies, obstacles, and challenge markers. There is definitely some degree of variety in the level layouts, but none inspired any real excitement, since there were no distinguishing structures or anything eye-catching. There's not a lot to visually distinguish the levels outside of the colors, as basically all feature grassy hills and rocky cliffs.
Also shared between all levels are enemies which home in on your position when you enter their aggro zone, poles that send out shockwaves, poles with spinning bars, and water/lava. Challenge markers also offer little variety - some ask you to race to a flag in another part of the map, or navigate an obstacle course while its platforms are still active, or defeat a set of enemies within a time limit. The latter is no challenge at all, as you merely hop up and the enemies will find their way under your feet, provided they didn't get shoved off of the platform, rendering the challenge impossible to complete for the current attempt.
But the game is largely inoffensive, even if it is incomplete, and kind of simple. If you like 3D platformers, it's decent for being free.
