I want to throw in the fog-of-war alternative "line-of-sight", which would, depending on historical setting, be a "realistic" alternative to fog-of-war, but still enable surprise tactics and the like.

I come from the camp of Total-War and, uhm, Silent-Hill *ahem*, btw, and was never deeply in love with Dune-likes (except for Starcraft I and C&C I/II), so I am not sure if that's a good alternative.

*de-debunk*

Fog of war is tool that fills in several spots. Removing it means you'd have to consider these:

1 - Information. As Sun tzu says, war IS information (and RTS are part of the wargame genre). You need to find a way to deal with information in a genuine way that is at least as much fun (or people accustomed to the fog of war will simply complain there was no reason for you to change the core mechanics in the first place)
How interesting would poker be if cards were all put up? You lose gambling, and the psychologic edge to strategy (and yes, even a well designed AI can feel FEAR)

2 - Scattering. It is important to have goals on the map for the player to move his or her units out of his or her base. Resources are one way, but information is an indirect reason. While there is no numbers to be gained by doing so, information has direct consequences on your many choices, thus, on the outcome of the game. The player with the most accurate information is often the victor, especially because of the rock-paper-scissor rule. If you know some player is ready to do this unit, do that unit, and you win it out. Obviously, you don't want to be able to do that without comitting something to the game (getting information) otherwise, it would be boring.
To all of those claim it could be more like chess, think again. Chess is limited, there is no production involved, and it is a game of tactics, spending as well as possible the units you have, not expanding the economy or choosing what units to build. And yes, I won a chess championship for the record ;)

3 - Strategy. If the opponent knows what you are making, then everyone knows what each other fields on the battlefield. It thus becomes who has the strongest economy rather than who uses it most efficiently, and that, makes a boring game.

4 - Ranges. There was a massive design trend to expand on a rather unused concept in the last few years: sight and attack range started to diverge in such a way that artillery and certain other units required "spotters" (read, military units that go on the vanguard to give line of sight to units with long range but weak line of sight). This was one of the best improvement to RTS mechanics gameplay elements in a while. Removing fog of war disables that.

SO I'm not saying Fog of War is an absolute, but you'd better be damn ready if you're willing to remove it. Depending on the scope of the project, it might be an unecessary amount of work to face for the gain to be earned. To a seasoned RTS game designer, solutions might come more easily.

Maybe 15 years ago when I was a kid, I hated the fog of war and preferred RTS games that didn't have it. Today I am on the completely opposite side. The unknown makes RTS games so much more fun and exciting because you don't have all the information. If I can look at everything going on in my opponents base, know what type of force they are building up, and be certain to have full knowledge about where and when they are going to attack, that's boring in my opinion.


But here's an idea: why not let the player choose? Let them enable or disable the fog of war. Of course in single player games against an AI opponent, this makes the game much easier so you might want to take that into account. Or how about allowing players to build units or structures that actually generate fog, so that they can obscure their bases from their opponent and their forces. All the opponent would see would be a big foggy cloud moving in toward their base and have no idea what units were in the cloud. Maybe have four clouds attack from multiple directions at once, but only one or two of those have actual forces hidden in the cloud while the others are decoys? I think that might be interesting and somewhat original. I think the original C&C Red Alert game did something like this, but not very effectively IIRC.

C&C had shroud generators which were essentially what you are stating. It worked great because it was the only thing that worked against radars satellites, etc. BUT, this means most games won't have it, and your base location and assets will be revealed for quite some time before it happens. Most games wouldn't even get to the point where one player has the time to invest in that kind of technology...

It was a good idea, its just not as great as fog of war.