Tales of Phantasia should be a prime example of this. Should be ...
The story is basically the same as that of the game, barring a few minor differences of course. A band of heroes must defeat the evil sorcerer Dhaos, with much in the way of fantasy action shenanigans along the way.
Surprisingly, the whole anime actually works rather well as the plot doesn't really let up at any point, and because of this, watching Tales of Phantasia is more like watching a good action fantasy movie. In essence, the series is nothing more than an abridged retelling of the game's story, and while there are some minor differences, the essential points remain the same. The show doesn't really try to portray itself as anything that claims to have a degree of substance, and to be perfectly frank, this works far better than a faithful 13 or 26 episode adaptation.
Like many adaptations though, Tales of Phantasia looks and sounds better than it actually is, however unlike most others, the difference here is marginal. The designs are taken from the game, again with some minor alterations, so there's no real creative skill involved there. Where the show does shine though, is with the smoothness and fluidity of the animation. There is a lot of action in Tales of Phantasia, and the animation level never really drops in speed or quality throughout the show.
As for the sound, the music is either taken from, or inspired by, the game itself. Once again, the fact that this is an adaptation places certain creative restrictions, however the choreography is very good, especially during the more frenetic scenes. In addition to this, the acting is actually pretty decent throughout. Since the original game didn't really feature any voice acting, there was a certain amount of freedom in choosing the right actors for the roles. While the are some minor niggles here and there, the seiyuu are generally good in their portrayals of Cless, Mint, and the rest of the gang.
To be honest, I wasn't at all sure I would enjoy this the first time around as I hadn't played the game at that point (I have done so now though), however I found that this didn't really stop me enjoying the show as long as I didn't try to treat it as anything more than a decent action fantasy. In that respect, it works surprisingly well as entertainment, in particular because there's usually something interesting going on in the show, one of the advantages of the abridged format.
While I know that there are numerous people out there who will decry Tales of Phantasia for "not having enough plot" or "not developing the characters", I should point out that if one is watching a show in order to be entertained, then such things are not always necessary. In the case of this OVA for example, the length of the series prohibits any serious development, yet the fact that the whole tale has been compacted into an easily watched anime means that the story is accessible to a far greater audience than before.
Tales of Phantasia is a rarity in game adaptations, not simply because it really is entertaining, but also because it's easy to watch (there's a difference you know). Like any game adaptation though, the creative limitations sometimes leave one wishing for something with more bite.
