|I've now beaten all the main 25 levels and 5 bosses, and started to 100% each of the levels. |
The blue relics in each level are a time trial thing. If you beat the target time, you get a sapphire relic. There's also gold relics, which have a much harder time requirement... and according to a walkthrough, there's platinum relics as well, which requires a practically flawless run. All sapphire medals are required to unlock the true ending, and all gold medals unlock a bonus scene, but it looks like platinums don't unlock anything.
This game also adds a bunch of new abilities, ontop of the new abilities you got in Crash 2, you gain a new ability after each boss. There's the powered up body slam, the double jump (which stops all your momentum), the infinite spin/glide, the bazooka, and finally, a sprint button which you mostly just need for the time trials.
Also in time trial mode, some boxes turn into time bonuses, so breaking those boxes while running through the level gives you extra time. Gold medals require you to hit most time boxes while running most of the time and making very few mistakes... Platinum medals are just unreasonable to the point that I don't think anybody
So far I've 100% cleared the first 10 levels with gold medals. One of them I even managed to get a platinum on. I'm not worried about getting platinums at all though. The golds are plenty challenging enough for me. It seems the actual gems in this game are mostly easy to get though, compared to the previous 2 games.