If I need to talk about a game that "was a big part of your collection but nobody even kmows about it", Mini Ninjas is that title for me. I replayed this little gem over and over again and really enjoyed everything that this title got to offer.
It a mostly standard linear platformer with some actions put into it, but its also the combination of many fun things: the ability to get multiple characters, all with different playstyles; the wide collectibles and spells that enlarges your techniques in really creative way, the artstyle that creates both incredibly charming scenery but it's also able to create more stunning and sometimes creepy moments (the cemetery levels took me by surprise at the time). Not to mention that you can approach some sections as you want, either by going full on attack or trying to sneak through the enemy lines.... "it's like in metal gear or smt I dunno"

I remember spending ours on the cooler levels at midnight, trying to sneak on enemies either by taking control of the animals and turning into a rabbit, or just following the troops before backstabbing them.

Honestly it doesn't do anything stunning: it's just a simple idea with a simple but charming and solid execution. But honestly I respected that simplicity at the time, and still made me enjoy it.
It's not like the most revolutionary adventure around and it won't change your life, but it still a fun, overlooked little gem from the time it came out.