Idk what you precisely get as retro and how much level of aging you want, but:

• Ezio from Assassin Creed is in 3 games where he starts in his 20's and at the end in 50's.
• Geralt is around 94 in Witcher 3 and sure as hell sometimes behave like a cranky old man, topic of age also often came in talks especially with Vesemir.

Not protagonists but prominent characters:

• KotOR have Canderous Ordo who is at least 40 and Jolee Bindo who looks as he's in his 60's but might be older. Also Kreia in KotOR 2
• Mass Effect have: Zaeed - in 40's and playing the part of old grizzled veteran, Liara - around 100 but as Asari barely an adult, Samara - 800 so entering old age for Asari, often mentions it, Thane 39, so while not particularly old for his species old for his job (assassin), Mordin - in his 30's so very old for Salarian and this topic comes often, Wrex - over 1000 so ancient for a Krogan and plays part of the grumpy old man
• Planescape Toment, Dak'kon is old and that is mentioned. Protagonist of that game is also very old but due to amnesia and copious amounts of magic it's not very relevant.
• Dynasty Warriors have some old playable characters like Zuo Ci, Huang Gai or Huang Zhong
• FF10 Auron is in 30's but behave like he was much older