Star Trek

I'm guessing DS9's uniform standards included Tactical as part of the Command division, with a red uniform (hence, Worf's uniform was changed to reflect his new position when he became a crew member on DS9).  That would imply that Tactical is a seperate division altogether from Security (DS9's Michael Eddington wore a yellow uniform as a security officer).

Command: Red

Operations (Security/Engineeering): Yellow

Science/Medical: Blue

Yeah I can buy that since Worf was in red. Maybe Tuvok had to cover 2 departments then? And just decided to keep the yellow uniform so him and Kim can balance out the color scheme on the bridge somewhat. 

I think that the colors just help make tactical officers and engineers not look the same. otherwise, there would be no red shirts/yellow shirts (depending on whether we're talking about tos or not)

TOS: Yellow/Gold: Command

        Red: Operations (Security/enginering)

        Blue: Medical/science

In TNG they switched the red and gold and added tactical to the command track.

I think you hit the nail on the head. "Why are my torpedoes being buffed I need shield, SHIELDS!" 

Tactical and Security are two different things.  ENT Reid was Armory/Tactical officer (who performed security duties until the MACO were assigned). TNG Worf was Chief of Security (gold), DS9 Worf was Tactical Officer (red). VOY Tuvok was Security, with Kim & Paris splitting duties normally performed by Tactical officers. 

In STO, they moved "security" to red as a simple way of making the game mechanics work:
Tactical (space)/Security (ground) = Offence
Operations (space)/Engineering (ground) = Defence
Science (space)/Medical (ground) = Buff

One thing I've ALWAYS had a problem with is the names of the divisions... TOS Gold/TNG Red shouldn't be called "Command" but rather properly be labelled "Operations" (meanind the duties neccessary to perform the primary OPERATING functions of running a starship, i.e. command staff, flight control/helm, navigation, weapons).  The Redshirts (TNG Gold) should be called Support or Services division. Notably the SERVICES that are required to SUPPORT the primary mission provided by "Command", being engineering, security, communications, logistics/supply/quartermaster.  Science/Medical is fine the way it is, but in STO I, personally, choose to make a distinction between Science (blue) and Medical (teal) uniforms.

Naturally, my reason for this argument is based on my real-world military experience.

http://images.wikia.com/memoryalpha/en/images/a/a5/Tuvok_2371.jpg

Tuvok was both Security and Tactical it was the reason I thought of this topic. Yes Worf was just the Tactical officer on DS9 and was in red but he did double duty on the Enterprise and was in yellow, so I guess when they have to work both jobs they stay in yellow. 

When doing double-duty, it probably depends on which is the PRIMARY duty (Spock wearing blue as Science Officer, for example, since his position as XO was in addition to and not his MAIN job.)

Well i always preffered gold for tactical because the first series i watched was Voyager. But I find red works just as well, In Game though i do stick to the TNG era colour code. I guess throughout the time-line Starfleet decided to change the colour code of its uniforms.