Since I was playing the Crash Bandicoot N. Sanity Trilogy (seriously, screw you revamped physics) I figured I'd share a small concept that I once thought of a while back if I were to do a hypothetical Crash game. It would be a celebration and merge of the best mechanics and features across the series into one megagame of reasonable length.
It would have the controls and physics of the third game but the overall presentation of the second, with the player in the memorable circular Warp Rooms with the entrances and exits modeled after the theme of the Warp Room itself. Like Crash 3, collecting five Crystals and finishing a floor and defeating it's boss would grant you an upgrade. And of course there's the trademark gems and colored gems, the latter of which are regulated to at least one per Warp Room.
The levels would use different themes from around the series, complete with it's appropriate music (including custom Bonus and Death remixes of Crash 1's themes). Below would be the main Warp Rooms and the levels they contain, along with their corresponding themes:
(these levels/level names/available gems would be subject to change)
(any level listed above with an asterisk has a secret entrance)
Crash is playable in every level, even taking the seat from Coco for the "Pirate" levels (though in keeping with the spirit of the N.Sanity Trilogy, she could be controlled as well). Levels with a second gem are earned through Death Routes, Colored Gem Routes, or secret entrances. These alternate entrances may or may not provide additional crates to smash to get the box gem (but in most cases they do not).
Once you conquer those rooms, you arrive at the eighth Warp Room, a dimly lit and ambient room with foreboding music and only one level, with a larger "gate" than the others:
This level would be about twice the length of your average Crash level, taking place in a brightly-lit golden ruins (in the style of the Golden Passage from Wario Land 4) finishing off with an optional multi-color Gem path, which in total triples the length of a basic Crash stage. From there you beat the stage, get the final crystal and gems, and fight the final boss.
Relics would be present, with the basic Sapphire/Gold/Platnium on offer for finishing a stage fast enough. Unlike the original trilogy, you can also get Relics without happening to initiate time trial should you complete it fast enough (but you don't get to keep track of time unless you get the goal time for a Sapphire Relic or higher). Your reward for earning Relics is access to an even larger circular Warp Room under the first Warp Room with four extra levels and three alternate entrances:
Secret levels accessed in the style of Crash 2's secret levels can also be discovered, with it's own giant-sized Warp Room. A total of four secret entrances and three secret levels can be discovered, with the final level in the room accessible by beating the three secret levels and getting their Keys:
After the final boss, you would also gain access to two post-game Warp Rooms, which in the style of Super Mario 3D World, offer harder alternate variations of existing levels and a new branch of "Totally" levels ala the ones in Crash 2.
And that pretty much coverts what I had in mind for this project.