Looking for a challenge? Well it's certainly not here.
But I wish I hadn't.
You play as a lone predator removing any evidence of the Alien species that has crash landed on Earth. Hordes of Xenomorph warriors and human soldiers do battle with each other and you if they get the chance. While you deal with these foes you must also (or so the tutorial says) use a solvent to dissolve any dead facehuggers you may find, however this is just a big waste of time, just like the whole combat system. To blunt: you won't be challenged for a second. Exp is always readily available and it is spent on upgrades whether you like it or not and you are massively overpowered against virtually everything that moves anyway.
If you get stuck in the game a big shiny triangle appears on a wall telling you to break it, removing any remote chance of puzzle solving and creativity.
The graphics in Requiem are ok but could be a whole lot better considering the psp's engine, and the music is repetitive and gets on your nerves after a while and the scenery is dull and also repetitive.
The enemies you face come in 3 flavours: soldiers, aliens and spikey aliens. That's it (civilians don't count). And no, other than a choppa there are zero boss fights.
All that being said you do get to be a Predator with cool technology (but you won't use it) and you get to choose what path you take, like through the forest or sewers (but it all leads to the same ending (and it's disappointing)).
In the end Aliens vs Predator: Requiem is a rather mediocre game and you may as well spend your time doing something useful (like spelling swear words on a calculator) than playing this.