This is the second of N. Sane Trilogy's DLC levels. While Stormy Ascent was a nearly-finished level for Crash 1, Future Tense is based on another scrapped Crash 1 level called "Waterfall", but then Vicarious Visions revived this plan and completely reconstructed it into a future city level for Crash 3.
I don't think this level is as difficult as Stormy Ascent is, but it's still one of the harder levels you could encounter in the game. You can play this level as soon as you download at any point of your playthrouh, but it is extremely-recommended to wait until you get all of your powers for it. On top of that, it's also very long if you're trying to get both of its Gems.
And you very likely will, because the challenge Gem is found from a Death Route, meaning you need to reach that Death Route without dying beforehand, and that route has its own crates that you need to break. A "!" switch crate you can find beforehand can only be hit with the Bazooka, which will then reveal an iron Arrow Crate that takes you through the path that leads you to the Death Route's platform.
The Bonus Round also requires some good time on your part with how you must both use and not use a TNT as it's gone through a Slot Crate.
I've already maxed out my completion rate to 105%, but getting both of this level's Gems kicked that up to 107%!