"Single playthrough" refers to completing a game, movie, or story from beginning to end in one continuous session without stopping or replaying any parts. Full definition
It can easily be beaten in 10 to 12 hours of gameplay, though it offers some replayability in the form of a host of mini cutscenes which can not all be unlocked in a single playthrough. (gamingtrend.com)
With a see - sawing episodic rhythm that visits some starkly different locations and play styles, a wealth of incidental and hidden detail, more gameplay mechanics than you can fully explore in a single playthrough - and above all, an epic, elegiac, arcane storyline that seeks to tie up every last loose thread and honour the passing of a classic videogame hero - Metal Gear Solid 4 is, in most senses, the biggest Metal Gear yet. (eurogamer.net)
Plus, as much as I like trophies, I have so many games that I want to play, I can just concentrate on enjoying the single playthrough (which is also fine by me, I don't revisit many games) and not worry about what awkward ways I might have to kill 3 zombies simultaneously with a weapon that requires a particular XP level, whilst standing on my hands. (thesixthaxis.com)