The first few years of the PS3's lifespan were rough. Despite exclusives like the first Uncharted game, A Crack in Time, or Metal Gear Solid 4, it was still struggling to gain a foothold against the constantly growing library and userbase of the Xbox 360. While things eventually ended up more or less even between the two systems in the end in terms of worldwide sales, the PS3 needed as many exclusives as it could get early on if it hoped to compete. One such exclusive that it could forever hold over the competition was Demon's Souls, FROM SOFTWARE's spiritual successor to its long-running King's Field series.
This hardcore and brutally unforgiving action RPG stood in stark contrast to many of the trends that occurred throughout the generation, namely the streamlining of games and reducing their difficulty in order to broaden their audience. Demon's Souls is incredibly unapologetic in its design; it is an action RPG for those who enjoy challenging action RPGs, and, if you don't take the time to get over its learning curve and learn its rules, it makes no effort to accommodate you. It is these aspects that most stood out about the game upon its initial release, though challenge alone is not what makes Demon's Souls a good game. The online multiplayer aspects were revolutionary in many aspects, with players able to summon or be invaded by phantoms "coming into their world" to help or harm them. While many critics of this generation praised games like Journey for their innovation by including seamless multiplayer without lobbies, it was Demon's Souls that first offered this type of multiplayer, and it is part of what makes Demon's Souls so memorable.
Multiplayer aside, the game is incredibly tightly designed. The game features five worlds, each broken up into smaller segments that are focused on specific challenges, such as climbing a giant tower with demonic gargoyles perched upon its ledges, or the infamous poison swamp. Just like an old school NES game, enemy placement is deliberate and methodical, and each enemy is meticulously placed to add to that level's specific challenge. Levels are filled with secrets and shortcuts, harkening back to the depth the best older games had to offer.
In the interest of avoiding too much wordiness, it would be easy to sum Demon's Souls up as this; it is an unapologetically challenging game that isn't afraid to punish players who don't take the time to learn it; it has a beautiful, dreary, and haunting atmosphere; the flexibility in its levelling system and weapon types enable a high amount of replayability and variety of ways to tackle the game; its level-based structure provides for very focused and tightly designed challenges; and its multiplayer offered something truly unique and as yet unseen in the era. With all these things in mind, it is easy to see why Demon's Souls made it on the Top Games of the Generation list.