We have here something big: The start of a subplot. This is effectively a scenario similar to "The Ticket Master", where a big event is set up to happen later. Now, "The Ticket Master" wasn't particularly big in itself, partially because it came out far before S1 hit its stride. Still, it's hard not to feel annoyed that our return to the Crystal Empire is done in such a derivative, obnoxious manner.
Even when I first watched "Games Ponies Play", I identified it as a fairly typical comedic misunderstanding plot. As far as stories go, this is about as standard as it gets. Now, it's not inherently bad that a plot episode uses such a generic structure, but this particular tired joke isn't particularly funny at first and it gets incredibly grating by the end.
Something that makes this even worse is that the episode is badly written. Dialogue consists primarily of endless streams of pronouns, and everything said is just distractingly vague. The only way this could work is if, by some contrivance, nobody ever mentioned Ms. Harshwhinny's name, occupation, or reason to attend. Of course, that's what happens, and it's dreadful. There's something uniquely intolerable about watching characters make that one stupid mistake for the entirety of the episode, and that it requires such terrible dialogue in order to work is unpleasant to say the least. Even the reason for why the wrong pony is picked is dumb. I mean, who would think to identify someone based on the pattern of their suitcase?
The episode is at least gorgeous, which is a definite point in its favour. The Crystal Empire is as pretty as ever, and while visual creativity isn't especially present here, there's still something to be said for the sheer level of craft on display here. Detailed animations, pretty designs, and a fair amount of energy all work in the episode's favour. There's also a few decent gags, though they dry up about halfway through.
As a side note, at least on Canadian Netflix the audio quality of this episode is horrible. Everything has a tinny sound, which despite all my efforts never went away. Only "Games Ponies Play" was affected, making the experience of watching the episode surreal at first. Ultimately this didn't detract from my enjoyment of the episode (or lack thereof, as it may be).
Now, for the consecutive story thing this episode has with "Just for Sidekicks". The earlier episode made far better use of this, as even though both episodes only featured the crossover proper at the very start and very end, "Just for Sidekicks" at least felt like the crossover mattered, Spike & co. visiting the Crystal Empire further into it. In "Games Ponies Play", the fact that it occurs consecutively with "Just for Sidekicks" doesn't really matter, being more of a neat Easter Egg than anything. It's disappointing, and probably why this wasn't attempted again.
Ultimately, though, unlike "Just for Sidekicks", "Games Ponies Play" doesn't stand on its own. It's simply not a very good episode. The tired joke at its centre would be bad enough, but it's surrounded by bad writing and an obnoxious level of character stupidity. This was a major plot episode, and that they didn't do anything of interest with it is a disappointment.