It's been quite fashionable to blend game genres together recently, with tower defense gameplay being one of the more popular things to throw into the mix.
Coffee Stain Studios' Sanctum was one of the better "hybrid" games out there, incorporating a combination of both conventional tower defense gameplay with fast-action first-person shooting. It was fairly well-received by players and press, and clearly sold enough to justify the developer working on a sequel, which came out earlier this year.
Sanctum 2 attracted some criticism from fans of the original, however, because it had been significantly rebalanced from the original game. One of the most obvious differences from the first Sanctum was that each level now had a hard limit on the number of towers that could be placed, meaning there was a much stronger emphasis on players (plural, because the game was now set up with a clear focus on cooperative play, too) inflicting damage on the incoming creeps as much as -- if not more than -- the towers themselves.
Alongside this, the means through which resources were distributed also proved controversial -- players weren't automatically given the blocks and money required to purchase towers; it was instead left to them to decide among themselves who got what, or simply race to be the first to collect them.
The game actually turned out to be pretty great -- I played a bunch of two-player co-op with a friend shortly after it came out, and it was a lot of fun -- but some people were still unsatisfied by what they saw as arbitrary limitations on a game they would otherwise enjoy. It's easy to see why; they were expecting Sanctum 1 with better visuals, and what they got instead was a very different game. I also actually agree that the resource "allocation" system is inherently flawed, particularly if you're playing with random strangers who are inclined towards griefing. But still, these flaws weren't enough to spoil my enjoyment of the game.
Coffee Stain Studios has, it seems, been listening to fan feedback, because it's implemented a new game mode into Sanctum 2. Sandbox Mode, as it's called, allows players to take complete control of their experience on any level previously completed in the campaign.
The game mode tasks players with surviving for as long as possible against endless waves of enemies, and allows you to tweak a number of options. These include how resources are gained, how strong the enemies are in terms of health, and the ability to turn the tower cap on or off, effectively allowing the game to be played more like the original Sanctum if desired.
"We continually want to improve our game based on feedback we get from our community," said Armin Ibrisagic, PR manager and game designer at the developer. "It's our way of thanking players for supporting us."
Sanctum 2 should be updated today with the new game mode on both Xbox 360 and PC -- it's a free update rather than premium DLC. Coffee Stain Studios notes that the second full DLC pack will be available for PC in the near future -- the first is already available -- and when it's eventually released the first two DLCs will be bundled together in a single pack for Xbox 360 players.