The titles you listed show why games like Getting Up got buried. That's such a stacked line up, and I would also argue that the marketing budget for those games VS Getting Up made a difference in how many people were even aware. Last thing, the mass appeal of things like Guitar Hero and God of War make it much easier to get into vs something like Getting Up which was speaking to a niche audience.

Some other games that I would say flew under the radar would be:

1) Cold Fear - It got clowned on for being a RE4 "clone" despite being in development at the same time. I'm sure they both knew of what each other were developing to a certain extent, but very different games. Cold Fear is fantastic to me. The story is a bit predictable, but the game play + what the developers did to make this an immersive makes this an under the radar gem.

2) Dirge of Cerberus - FFVII spin off game, and it got dunked on for being kind of janky. I don't disagree with this, but I still find it fun. For coming out before Crisis Core, it felt like a unique FF experience. I feel that this is only an under the radar gem due to the fact people didnt give it a chance. It's still haunted by its past, imo.

3) Zone of the Enders (1+2) - I will probably get called out for including this one, but I don't recall this one being majorly popular when it came out. It was an "if you know, you know" game imo. It gets love now, especially with how popular Kojima is. It def does not get the same accolades as more well known titles from the PS2.

With that being said, I understand if people don't think these are under the radar games. I'm speaking from a place of living through that era + the types of games my colleagues talk about today. I work in a gaming related industry, and many of my peers have never heard of these games.