In no particular order;
1. Dark Souls II - Set me on the Souls series which in turn inspired my writing which eventually got me to go back to university. Also got me into Berserk and similar media.
2. Blasphemous (1 and 2) - As above, inspired my writing which got me out of a huge funk I was in.
3. Elden Ring - As above, inspired my writing and got me through a rough period of my life in which I was working a dead-end job and was experiencing a lot of mental health issues.
4. Warhammer 40k, the table-top game - Got me out of my shell and into meeting new people.
5. Dungeons and Dragons - Same as 40k, I met a lot of my best friends through it.
6. Devil May Cry 4 - I was like, 10, when I played it and it set me down an urban-fantasy rabbit hole my entire life. Should I have played it at 10? No. Did it set up my interests and hobbies well into adulthood? Yes. Also got me into nu-metal and light metal genres which had an insane knock-on effect. You had to be there in the early-to-mid 2010s for AMVs.
7. Witcher 2 - Same as DMC4. Also inspired me to look into folklore more.
8. To The Moon - My now-ex-fiancée made me play it to understand her better (she is autistic too), helped me understand myself better too. The narrative was also just incredible and beautiful.
9. Fear and Hunger - One of the greatest RPGMaker games in my honest opinion, inspires a lot of my writing and is just inspiring generally as a creative.
10. Overwatch - I met my boyfriend through it, so it has to be life-changing by virtue of it.
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Struggle, endure, contend, for that alone is the sword of one who defies death.