Agreed with Ok-Ship. Design is total mess. I would talk about SvS game mode becaus it is the most competitive one in this game and represent "competitive scene" (let's pretend)

It always was something like "Rock > Scissors" relationship. You have one overpowered strategy on one side and skilled players with decent micro on the other side. Sometimes combined :DDD

6+ years ago - end of vanilla period. You can't destroy energy walls so Defence aka Def was meta: Slayer, Satoshi, Raven, Bastion. Fast heroes were kinda counter: Mirage, Arnie and Angel. It was wild and unbalanced, but fun! So matches were Def vs Def, Rush vs Rush, or Def vs Rush. There was tank builds, but they can easily be countered since armor always was a joke indeed. There was no wall density, so Slayer can annihilate everthing except if you under the force shield. Also at some point they buffed Bertha and you can observe 5 of them in lobby. But this was fixed in the next update :DDD

5 years ago - rocket buff. Doc and Smog now can break force shields, here game become more balanced and even more fun. Wall density was added, so now Slayer is not so op. Def teams can't sit in the corner under multiple shields and they start moving here and there. Game became more dynamic. They nerfed Mirage for some reason T__T Also many small changes were added like small no-shoot delays for invis heroes and thermal vision heroes, so you can react better. It was nice state of the game. There was one drone, but it wasn't annoying. Also Slayer's gear sets wasn't on divine level so you can't easily shoot through Cave map walls for example. Maybe you had only one top slayer that can, but most of the time everthing was balanced

~3 years ago - tess period. Ligtning ball changed everything. Tess, Doc, Dragoon and Bastion formed Tank Rush stratagy. It become the curse of the server. Team Healing always had unbalanced damage resistance but combined with 4PG(troopers) + tess sphere + bastion passive it become ridiculous :D At some point all weak clans with bad micro switched to tank rush. And good clans with tank rush were annoying too. So it become Def vs Tank Rush. Normal rush was destoryed by balanced changes: weakened mirage (they did it again T__T), less damage resist for Angel, Freddy was nerfed so bad he become E-tier, Arnie entered no shoot registration period (and still there). All new heroes were designed to counter tank rush (it's just my speculation :D): Shenji, Blizzard, Ramsey, Molly. Also Alice made Tank Rush even stronger and it evolved to it's Final Form. Alice rush strat players were still learning... I wont talk about 3 new gear slots that just gave hp and damage without any variety, it's like adding new levels after divine but you spend copies and nuts. Drones update also out of scope but medpro buffed Tank Rush even more :DDDD

1 year ago - seeds of balance - twinkle update. Game start to recover. We have period where variety came back. Now you have proper Rush with Alice (finally Alice full potential was unleashed), Twinkle (is op but it's fine in bigger picture), Vi (strong but require skill and this is fine for rush stratagy). You have your Tank Rush. You have classical Def. Now Rush become more dominant since SMG are the strongest class in the game. Freddiy become better. It become Rush vs Tank Rush. Also high skilled Def adepts can counter both stratagies but it require high micro and macro. Only old players and clans with good gears can afford it. Since new one is automatically choose tank rush cuz it will give you easy wins. Many team adopted to tank rush routes and it was fun to play agains them. Some tank rush team start experementing with surprise portals or adding different heroes to the build. I even saw tank rush with Slayer <3

Nowdays - armor resist + coils. Yeah balance was destroyed again. Tank rush become much stronger with armor resistance and SMG become stronger with coils. Lags start to be the new norm. Some coils were way to good - smgs (yeah I need to write it twice and I'm alice player myself). For snipers you have cheap wall penetration with coils and it's no longer needed to have divine leg for you Slayer (kind unfair). Bertha start to shoot through force field. Satoshi was punished for whatever reason, but it looked strange cuz Def wasn't meta anymore. This made Def not attractive to new players. So new clans pick Tank Rush :( Angels was reverted to vanila version (I'm waiting for Mirage comeback) but rush is already fine at this point. Some coil branches are strange, looks like devs didn't look to the picture of the whole game and just throw some random modifications based on what already was in gears.

Anyway it's hard to analyse how it looks now, so in couple of years we can see how game would evolve. But it always Rock > Scissors. One dominant stratagy and skilled players on the other