I've updated my puzzle to make it a little fairer:

The forgotten letter has now changed to:

This letter's in the phonetic alphabet as a city in Peru

so you might want to go back and have another look at it! :-)

And the answer's in the most common Steam 5-5-5 format.

VWAAV-EVAWT-N2L

If anyone's really stuck on the last clue, I can provide a very subtle hint :-)

Would be nice :)

How'd you come up with A for the phonetic synonym for father?

-edit NM i see it now

Pasadena, California

Said it would be subtle -- but I've checked, that's enough to get you the answer if you've read the clue carefully enough! :-)

EDIT: Oh, and I'm not commenting on whether any guesses are right or wrong! (About any of the clues) :-)

Hah well there's only one famous hard rock group from Pasadena, so some of the previous letter I got must be wrong
OR.... it's reallllly subtle

The key word may be, seemingly

Got it, thanks! Looks like an interesting Rune-ish game, and I'm curious to try it out!

For the curious, the band was Van Halen, the letter was L as in Lima, and the dance was Foxtrot :-)

Congratulations! Someone solved it at last! :-D

For those who are interested:

Initials of German car manufacturer VW
This letter is a synonym for "father" in the phonetic alphabet P (Papa)
Initials for a system you can see and hear AV

Initials for an astronaut's spacewalk EVA
Letter for alcoholic drink in the phonetic alphabet W (Whiskey)
This letter's a bit of a phonetic dance too! F (Foxtrot)

First letter for the only month in the phonetic alphabet N (November)
? can be as bad as one. It's the loneliest number since the number one 2
This letter's in the phonetic alphabet as a city in Peru L (Lima)
These two are the initials for a seemingly-driven American hard rock band, but in reverse! HV (Van Halen)

Still, I'm not sure about the "seemingly driven" reference. What is it about?

Because they are "driven" by the keyboard / lyrics / guitar or something
I had Tango, not Foxtrot :(

Van

It seems to be in use in various English-speaking countries as a type of vehicle.

Hm, yes, quite droll, indeed. :P

Here's a nice easy one: Zombie Bowl-o-Rama (Steam)

Key attached as image

Shit! is gone, not for me :/ thanks for this giveaway!