Disclaimer: I've only used games I have currently added to GDNA. I still need to go back and add all pre-PSX era games I've played, so please keep this in mind. ^^ Also, the games are listed in no particular order.
Ar Tonelico: Melody of Elemia
Influential aspects: music, emotion
Ar Tonelico resonated with me on many levels, but hit me especially hard from an emotional perspective. I found it absolutely amazing how I was able to identify with one of Lyner's three datable Reyvateils - Aurica. This identification pushed me to learn more about her and pursue that relationship specifically. Putting personal resonance aside, the three characters seem to embody very specific archetypes, likely in an attempt to appeal to, or connect with, a larger audience base. An undeniably brilliant move.
Ar Tonelico's music was also a turning-point for me. All snobbery aside, I like to consider myself fairly well-educated when it comes to video game music. I have a rather large collection, and listen to it as my genre of choice. Ar Tonelico blew everything I had previously known out of the water; most notably the hymmnos - very specific, powerful songs sung by the Reyvateils. From the opening lyrics and channel-swapping of "Expressive Hill -Harmonics EOLIA" to the layered vocals "EXEC_PAJA/.#Misya extracting" and "EXEC_PAJA/.#Orica extracting", I continue to listen to these tracks and find myself discovering subtle nuances and artistic flairs.
The "EXEC_PAJA" songs in particular exemplify the sheer dedication and attention to detail in the music creation. Aurica's PAJA has faint bells throughout, slight percussion and lyrics tinged with sorrow, pain, and hope, while Misha's PAJA has extremely strong percussion, a pulsing dark beat, and angry, aggressive lyrics. In both these tracks, vocals at differing tempos are layered with seemingly different words that meet up on the occasional word or phrase. It's hardly something that can be explained and must be heard to be understood.
Influential aspects: story
Xenogears is an incredibly complex, beautifully executed game that redefined for me the types of stories video games are capable of telling. On a personal note, this was likely the first time I had experienced a game that presented such a convoluted, thought-provoking, challenging storyline. Presented as the "reluctant hero" type for a majority of the story, Fei's multiple personalities and complex interrelationships creates a sort of perpetual motion throughout the game that drives you ever forward. I personally find conditions such as MPD (multiple personality disorder) to be absolutely fascinating and should probably note that being able to witness and understand such dramatic changes between Fei, ID, and the Coward provided me with a sort of guilty pleasure.
Because I fear giving too much away, I'll just state that the heavy religious overtones, psychological disorders, implied time-loop, and dark plot weave together a completely enthralling experience.
Shin Megami Tensei: Nocturne
Influential aspects: presentation, story, gameplay
Shin Megami Tensei: Nocturne was actually the first game I played in the SMT series (excluding Persona 2: Eternal Punishment), so it's no understatement to say that the game completely shocked me.
Nocturne's premise is the destruction of Tokyo to create a new world (known as "The Conception") to be guided by one of the few "chosen people" with demon's under their banner. Not only does this premise shock, it creates a post-apocalyptic world I had never before envisioned or experienced in other games. On top of that is the fact that the few people you have interactions with prior to The Conception become incredibly central players to the storyline.
Now take this already dark, potentially unsettling atmosphere, and throw in the main character's demonic transformation, pacts with demons, the biblical Metatron and Satan (depicted not quite as you would imagine) and you have yourself one "hell" of a story (pun intended). In all seriousness, though, convincing demons to join you, fighting off horsemen of the apocalypse, and watching how a transformed, primal world alters the few inhabitants left is an unbelievably mesmerizing experience. This isn't even bringing up the gameplay mechanics that effectively turn each boss battle into a puzzle. ^^
Silent Hill 2
Influential aspects: atmosphere, emotion
Silent Hill 2 was actually my favourite of the series, which I also consider to be the most influential, despite having played Silent Hill prior to it. Not only is the town rendered in a much more phantasmal sense, but the connection between the twisted denizens and the protagonist's guilt and pain is incredibly apparent, not to mention extremely poignant. Pyramid Head in particular personifies the hero's belief that he needs to be punished for his sins, be they real or perceived. And the game freaks you out in doing so.
The complex emotional relationship between James, Mary, Maria, Angela, and Laura also worked beautifully as each of these individuals were characterized in relation to James in their own way. This multi-faceted relationship tweaks the emotional aspects of Silent Hill 2 to nearly unbearable heights at times. More than anything, I find myself drawn to the personal touches and connection in this installment.
Influential aspects: gameplay
SaGa Frontier was my first foray into the Romancing SaGa series. (excluding the games on the original Gameboy that were rebranded to "Final Fantasy") SaGa Frontier was incredibly unique in its overall execution - not only are you able to pick which character you start out as (out of eight, I believe), but the gameplay is completely open-ended, allowing you to pursue the sidequests you wish, and acquire the spells and abilities you desire.
Which brings us to combat - what I absolutely adored about SaGa Frontier (and the other Romancing SaGa games) was the "sparking" mechanic. "Sparking" was a means of learning new abilities that took your specific weapon type such as swords, martial arts, guns and so forth, compared it to your frequency in using the weapon set, factored in the difficulty of the enemy, determining whether or not you would learn a new skill. For instance, you could just go to punch an enemy, but all of a sudden end up with a multi-kick ability or a throw. This, for me, brought a sense of wonder and delight to even random battles, knowing that in each encounter I had an opportunity to learn a new and exciting ability. I recall my heart jumping several times as the light-bulbs swirled above my characters' heads.