A terrific story, one of Troughton's best.

From the first minute after the title sequence, you know that the showrunners knew they were onto something special, with a bombastic flashing title card amidst explosions and gunfire. Then, our gang seems to be thrust into the middle of a typical historical set in WWI. The viewer pre-emptively braces themselves for 10 episodes of wacky misunderstandings and hijinks, and mutter "please don't become another base under siege...".

That is until we are shown that something is very, very wrong with this war zone (aside from the usual fighting and death), as the clearly villainous English general sends a message to his (definitely alien) superiors, accompanied by some wonderfully ominous music from the Radiophonic Workshop. As the Doctor and his companions continue to fight for their lives, things keep going hilariously wrong (Romans appearing out of nowhere is now one of my favourite cliffhangers in Classic Who). After 3 episodes, the story completes the transition from weird historical to fully high-concept sci-fi, as the Doctor and Zoe travel in a TARDIS-like machine and arrive in a thoroughly alien, probably fascist, command centre/weird goggles convention.

The mysteries don't end there, however, as we get a very slow tease that there are other members of the Doctor's race, plus some wonderful former-best-friends-maybe-boyfriends/proto-Master chemistry between the Doctor and the War Chief. This is followed by several episodes of (to simplify) an intense cat-and-mouse game between the two, while in the War Zones, Jamie employs his usual Scottish charm to galvanise the Resistance into action. (They are in small groups, and engage in guerilla warfare, I wonder if that could symbolise anything in 1969...) Though, points get deducted as we get an instance of "black character dies first" as part of a tragic racist streak in the Troughton era, and Lady Jennifer, who has been a wonderful addition to the group so far, gets sidelined as she gets back to her """womanly""" job of being a nurse. Things are also not going very well at the School for Spiral Enthusiasts as usual fascist infighting/mutual distrust ensues between the two Chiefs, and they are forced to summon Daddy the War Lord.

All of this culminates in an epic, sweeping climax as the Resistance begins a coordinated effort at taking down the sci-fi incel rally... except it is interrupted as the Doctor realises just how bad the situation has gotten. What follows is possibly the greatest half-hour of Classic Who ever. The Doctor has uncharacteristically lost all hope, as these mysterious Time Lords yield never-before-seen power, vanishing people into thin air while pressing the "0.5x" button on their tape of the episode. They disable the TARDIS, destroying the show's format. They also un-do a season's worth of character development for Zoe, and separate the Doctor from his boyfriend. While the Doctor tries to maintain an air of optimism as he says his goodbyes, he knew the cruelty of the Time Lords only too well. (Troughton's delivery of "They'll forget me, won't they?" is heartbreaking)

The episode ends with our hero on a screen, screaming into the void, never to be seen again (except, not really)

The War Games uses its 10 episodes excellently to tell the story of one of the Doctor's greatest failures. It thoroughly re-invents the show, but not before telling a story of an elite who make war and brainwash the young, not for any ideology or injustice, but only out of a desire for power, and an utter disregard for life. In 1969, it is hard not to associate this with British diplomatic support for the US in the Vietnam War. The Doctor can do his job and get rid of the monsters, but is utterly incapable of dealing with the messy aftermath. As punishment, everything he loves is ripped away from him.

Regeneration stories rarely get this good.