The comedic episode features Captain Kirk in a battle of wits against titular character, a part played by William Campbell, a friend of the cast and crew. Written by Paul Schneider ("Balance of Terror"), it contains several of the plot elements in "Charlie X" but is quite a change of pace from the seriousness and dreariness of the first half of Season One with Star Trek making a concerted effort to lighten up. (In fact, the two episodes before this both end with forced laughter, with Scotty nearly falling over in a fit of giggles at the close of "The Galileo Seven". And this is after the deaths of two crewmen!)
The Squire himself, "Trelane", is sort of an interstellar version of Liberace, full of energy and delight and devoid of Charlie's uncertainty and longing. The idea of a serious Captain faced with a more powerful but whimsical adversary is one Star Trek gets a lot of milage out of, and it works here right off the bat. Trelane does what no crew member could get away with, having fun at Kirk's expense and making fun of his people. With Star Trek's original audience including many kids (especially boys), it a great way to connect with viewers; what young fan wouldn't want a chance to play with Kirk and the Enterprise as if they were toys - or at least see someone do it? (The script even borrows from "The Most Dangerous Game" with an outdoor hunt... though it's unfortunately shot on a stage). Meanwhile, the wardrobe department and the set designers get a chance to let their hair down, with Trelane favoring an antique look that's a nice change of pace from the spartan designs of the Enterprise. (The music is also a The question, of course, is "what's it all leading to?" Whereas TNG stretches the Q issue throughout the entire series, this episode puts a cap on the Trelane, coming up with a satisfying conclusion that, like a Twilight Zone ending, changes the perspective of the episode and makes sense out of the madness.
Remastered Version: There aren't many special effects in this one other than a sequence where the planet Gothos actually chases the Enterprise around for a bit. The original sequence is actually pretty good. though the planet appears a little translucent (it was probably printed at less than full opacity to hide matte lines). The new effects more or less copy the idea of the original, but show the engine nacelles in the viewscreen when applicable and include a fully opaque, more realistic planet. Unfortunately, as in "The Conscience of the King", there's an unusually slow fade that throws the CGI team off, forcing them to fade into a shot of their updated Enterprise early, which looks awkward. (Again, the problem is that any fade from a character to the original footage of the Enterprise is unusable footage for this project and can't even be used for a crossfade into the new CGI Enterprise. The only way around this would be to create a CGI version of the original footage of the characters, giving them extra footage to use for the fade into the CGI Enterprise, but that would be expensive and eat up most of the budget for this project). It is notable that the team leaves the aliens at the end alone, a cost saving decision made easy by the fact that the original effect works just fine.