Lets go over the positives that team deathmatch currently has.
Team deathmatch is Team based
Social experience, which naturally attracts more players to the game. A lot of people wont play a game if they cant play with friends.
Team Deathmatch is Competitive
Can easily support ranked play. You can quickly have people coming to your forums to complain about ELO hell in a matter of days or weeks. You need this to happen believe it or not.
Team Deathmatch Encompasses all aspects of the genre with very few short falls
Weapon and armor pickups are fully supported with no change to the fundamentals of an arena shooter. Control of a level is based around these pickups as well making for varied play. Strategies emerge almost automatically as a result.
Lets compare TDM to other game modes:
1v1
1v1 is perfect in every mechanical way. Its weaknesses are that it places great pressure on the player with no way to blame others but themselves. Stage fright is a big problem in 1v1.
1v1 is not a social experience where you group up with friends to play together. A lot of people wont play a game if they cant play with friends.
1v1 fully supports ranked play, but it should not be the main game mode of your game for the above reasons. It can still be considered an optional core game mode however.
CTF
CTF is mechanically flawed in that it is prone to various game play problems. It is prone to stalemates and confusion. These are especially bad when one considers low skill players whom are likely not communicating very well. The mode is only good at high level play which is simply not good for anything with wider appeal.
CTF can be a social experience but the above issues negate any benefits of this positive point.
CTF can support ranked play but the above issues negate any benefits of this positive point.
Free For All
FFA is mechanically flawed in that you cannot play with your friends. It also tends to feel very random and provides a feeling that nothing matters.
FFA cannot support ranked play to any real degree.
Arena
Arena variations of the above modes are when you spawn everyone with every weapon in the game in set intervals and apply a last man standing mechanic. Arena is more or less a training mode for the game to help teach players how to fight each other but omits almost all aspects of the depth that an arena shooter provides.
Arena cannot support ranked play to any real degree.
So why do I bring this up?
Well, I had the observation that team death match as being probably the most important game mode of the genre based on the above points but is easily the most overlooked game mode as well. It holds all of the strengths of Arena shooters, while gaining the least attention in nearly every way.
For one:
Most levels for modern arena shooters are built around competitive 1v1. The vast majority of levels in Reflex seem to follow this idea. This also seems to be true for CPMA. The idea of doing 4v4 or 6v6 in most cases results in very crowded hectic environments. Quake 3 levels like camp grounds are fairly large spacially. A lot of Quake 3 level designs were better for Team vs Team game play yet even then 6v6 ranked play would likely be hard to properly do on those levels as well. Viable team vs team levels appear to be a minority.
Toxikk is one of the few examples where its core levels appear to work well in a team vs team setting at the cost of proper 1v1 support.
For two:
Weapons in most modern arena shooters appear to be balanced for 1v1 rather than team vs team. Evenly balanced weapons is actually less balanced for team vs team game play. Having some weapons that are dominant in very clear ways is actually a good thing for TDM. Its bad for 1v1 and is irrelevant in CTF or Arena however. It would actually be a good thing to include dominant weapons as a mechanic within TDM levels.
Again Toxikk is an example of an FPS where its rocket launcher was more powerful than other weapons in the game. Rather than embracing this people complained about it because they felt the gun was too good compared to other weapons. In a TDM setting the rocket launcher being dominant is actually a good thing. It punishes death more and makes it so teams have to coordinate to gear up. It makes map control more important.
For three:
TDM is overlooked for ranked play in general for unknown reasons. When you think of a Quick play option in your favorite arena shooter what mode do you imagine being the mode it picks by default? 1v1? CTF? something new? Quick play is not even an option in most games.
I seriously believe that ranked TDM with weapons and levels balanced specifically for TDM should be something people think about as a core mode for arena first person shooters. This means slightly larger levels and weapons balanced around dominance rather than equality. More prominent weapon tiers.
Now it may be true that an even more prevalent point is that every game should just have its own unique core modes like TF2/Overwatch/CSGO I have a pretty strong feeling that TDM is the payload of the arena shooter. And should be held to higher regard.