What does game "depth" really mean?

In my opinion, I believe that game "DEPTH" means that your body's ability to move can outpace your mind's ability move, thus forcing you to be a better thinker to be a better player

If player A beats player B, it needs to be because of a superior mind. IMHO, the only way to achieve this is to have speed and capability of the player limited only by their mind, and not by the physics. Best minds = best players.

Hmm, that's interesting, and I kind of agree with it. Generally games like Chess are thought of as requiring a higher than average cognitive ability, but the difference is in Chess you have 60 seconds to make a move, but in Nexuiz otoh, you have 60 milliseconds. Despite this, imo playing Nexuiz has nothing to do with your cognitive ability, but rather how well you know the map, the physics and the weapons. It's kind of like running (and a lot of other sports, for that matter): if you consciously paced out each footstep before you made it, you would end up flat on your face.

Which can pretty much be summed up as

Depth appears in games in the ability to practice certain things. These could be basic things such as movement or aiming, or more advanced things such as strategies and timings.

And generally I agree to your point. Depth means that you improve not by knowledge, but by "experience" - by getting used to faster and even faster action. Just, it is a lie that the current physics are way slower. In fact, with the current physics, I'd outrun you on any race (not CTS-only) map anytime, even while fighting. On racetrack I am twice as fast with current physics without even using the weird strafe-turning. On subseatrack I would estimate +50% to +100%, somewhere in that range.

And this is the thing, speed increases, but the skillpeed ratio decreases dramatically.

However, none of this should be "enforced" by artificially restricting the game! Additional lag in the game sure increases depth, as your mind suddenly has to work much harder. However, it sure is nothing we should strive for. Depth is something that should not be enforced by weird restrictions, but by "extensible" game design, by making MORE possible!

But there is a very fine line between making MORE possible and making ANYTHING possible. Iirc strafejumping originated as an engine bug, so it was a way of EXPLOITING the game, rather than a change introduced to make it faster. What if every piece in Chess had the movement capabilities of a Queen? Then it would just suck. It's fine to make it faster, but just saying 'Okay, now everyone can just turn as fast and hard as they want' doesn't keep with current gameplay. This is the issue I saw with Nexuiz, where all balance changes would be quantitative (ie. we need the mg to work twice as well, so let's double the fire rate) rather than qualitative (ie. the mg doesn't work very well at the moment, so let's make it do a bit more damage, keep the fire rate as is, and add a spool up time of 0.3s). For every change made, there should be an equal or roughly equal change in the opposite direction (ie. let's make the threshold for the point at which strafing is required for more efficient turning a bit higher, but make low range non-strafe turning a bit less efficient).

Edit: Realism isn't really the focus of Xonotic, but remember to 'keep it logical'