Out of all the games in this series this is the worst one to play. The other games were fun and each game let the player explore the planet and look for ammo, life, and money. With this game you have to keep returning to the same area constantly trying to defend it while trying to secure a new area or complete one. I would not recommend the purchase of this game.
I have been a HUGE Ratchet and Clank fan since the PS2 days, playing each game until every weapon unlocked and hidden item found. I found the gameplay very poor with the tower defense part of the game. There was NO feeling of exploration or discovery in this game as you were continuously having to return to defend your base. I returned the rental within days frustrated and barely completed two worlds. You can tell others hated it as well as it is selling on Gamefly for pennies on the dollar. I don't recommend you waste a valuable slot in your cue for this disappointing title.
I have them all with the exception of Quest for booty, even going back to all the PS2 games, this one is by far the worst. Its a different idea in the "tower defense" but the storyline is weak, the game is also extremely short(took me some 3 hours to beat start to finish), definitely not worth the $20 to buy, barely worth the rent for it. Very disappointed even though I knew what I was in for to an extent from reading other reviews. Ebay will be the next stop for this game.