They did introduce something new - but hardly innovative.  It turns out that the treasure is cursed, and all associated with it turn into the undead.  Yes, it's yet another game where you get to fight zombies.  These aren't the shambling hordes of Resident Evil, these are agile and quick and vicious.  These are just horrible.

While I did find the three-way battles between Drake, the zombies, and the mercenaries pretty clever, the general tone of the game was worsened by their inclusion.  I'm sure that many would argue that they were crucial to the plot - don't take the gold off the island, it'll make the world cursed! - but it could have just been a disease inside the golden statue instead.  Maybe it's just that I don't like things jumping out at me.

So, Drake went into the tombs, found Sir Francis, found the zombies, worked out that the gold was cursed.  There were some clever platforming bits around a 3D maze, where I had to follow signs marked either II, V or VII, which would have been a clever puzzle if it wasn't for the very obvious notes shown at the start of the section.  Unfortunately the platforming bits kept on being broken up by more mercenaries appearing from nowhere.  Also unfortunately, Drake died many times on the platforming bits because the controls are just a bit woolly.

Right at the end, there was a section where Drake had to chase the real enemy, and I kept failing it because unlike the rest of the game, there was a time limit.  I had to run past lots of zombies and mercenaries, shooting without aiming, and then jumping onto the treasure as it was hoisted into the air.  The final level thankfully had no zombies, but lots of sniping, rocket launchers, and an invincible enemy who ran from area to area.  The final battle had me foxed for a while until I realised I had to brute force it, rather than taking cover I just had to make Drake rush the enemy as he reloaded.

So, game finished, and I immediately went back to the first couple of levels to try to understand the plot a bit better, having forgotten about it in the years since I started the game.  I found a few more treasures by exploring, and was struck by how different the first couple of chapters felt, before gun-toting enemies turned up.  If only there was more of that during the game.

Anyway, while I've been a bit down about the game in my write-up, I was keen to continue it, and must admit that it's been well worth playing.  I hope that its sequels have learnt from the progression in game mechanics over time, and I'll move onto Uncharted 2 at some point soon.