I've exhausted myself searching these forums, BGG, the internet itself, and have been unable to find anything that explains how the Cover keyword, such as on the Cactus or Tumbleweed environment cards. They have hit points, so clearly they are susceptible to damage. But are they things a character has to actually declare they are taking cover behind? What's the deal with COVER?
If you look at Gunman and The Sheriff cards in Silver Gulch they have damage reduction based on the cover currently in play. So a Water Trough, Explosive Wagon, and a Prickly Cactus will give 3 damage reduction to the Sheriff and Gunmen.
As for the Tumbleweed, that's just thematic. There are loads of useless descriptors on cards; Train, for example, or Acrobat.
A lot of the Time Cataclysm deck's cards take keywords from other decks: "Cover" from Silver Gulch, "Agent" from the Block, etc. It's a sort of "when worlds collide" type environment, so it takes bits and pieces of other Environment decks and includes keywords purely for thematic reasons.
I just love the idea of Hero's facing off and a tumble weed just rolls across the field as everyone stares at it.
Reallt great thematic feel when you have everyone hoping for the Environment not to mess you over only to see this card.
...and hearing the theme to The Good, The Bad, The Ugly.
Even better if Chrono Ranger's on the scene, I suppose ;).
Thanks everyone. It was just that the word "cover" implies something that protects you, like, from damage. While it's funny, why does a tumbleweed have an HP? Is there any actual situation where that would come into play? Now that I'm writing it, I suppose for attacks that target things with the lowest HP, this would qualify in most cases. Anything else I'm missing?
As you say, from a mechanical standpoint, giving the Tumbleweed HP means that certain attacks will hit the Tumbleweed that might have hit a different target. I've assumed this is why the Cover cards all have low-ish HP, so that thematically they really are cover that absorbs attacks, without having to add an extra mechanic that is not on the cards.
As far as why these cards have HP, well, these Cover cards are none of them the most enduring of structures and will not absorb damage forever. Hence, as they are hit by attacks, their HP reduces, and eventually they hit 0 HP and break. From a mechanical standpoint, giving these cards HP is also a balancing factor, as it means there are two different ways to handle Cover cards - you can damage them, or you can affect them with cards or powers that destroy environment cards.
In general, Sentinels tries to have the rules that are not on the cards only be rules that govern the interaction between cards or other very base concepts like damage and HP, rather than adding extra options that have to be interpreted via keywords. Whenever you see a card with a keyword you don't recognize, it's probably best to check through the rest of the deck that card is in to see if that makes it clearer; and remember, there are a ton of "junk" keywords that don't currently do anything, like "Train" or "Dinosaur," that are just there a) for some humor and b) as an open door fo tinkering with it in the future.
One thing bugged me of the cover card. Like I would always think it would redirect the damage to the cover instead of a reduce 1.
Then again I could see how it could be bad for Explosive Wagon, but it just made more sense thematically.
It's not like it is total cover, like the Barrel is. I'm sure the heroes could easily shoot a ball of fire at the gunman's feet that were sticking out from beneath a wagon rigged with explosives.