Hard list to do and many entries are subject to change, but here it goes:
1. Horizon Zero Dawn - currently only for PS4, but soon coming to PC, one of the best game last year, stunning visuals, good story, great soundtracks and an ingenuous, tactic-based gameplay.
2. Witcher 3 - a close tie with no.1, while HZD has overall better graphics and game play mechanics, Witcher 3 excels in terms of story line and character development, however that is only normal, as W3 is novel-based.
3. Age of Empires 2 + Expansions - timeless strategy game, I recommend the Definitive Edition that Microsoft released recently, with HD, Remastered visuals and new content added; that's how you remaster a game.
4. Rise of the Tomb Raider - the best installment of the Survival trilogy, a larger map to explore, more collectible, more crypts and tombs to unravel, a fun DLC and great challenges, particularly Endurance mode.
5. Valkyria Chronicles - not that fond of Japanese games in general, but this one is very well made; turn-based, but with a good dose of strategy planning; every move and decision you make can influence the outcome of your mission.
6. Red Alert 2 + Yuri's Revenge - best games in the entire C&C franchise and I truly hope it will get a remaster treatment the way the first 2 got recently.
7. Assassin's Creed games - I will treat these as a franchise rather than classifying which are better; I recommend Assassin's Creed 1, 2 (+ Expansions: Brotherhood and Revelations), Black Flag, Syndicate, Origins & Odyssey.
8. Starcraft games - Starcraft 1, Broodwar and 2 (WoL, HotS and LotV), games made from a time when Blizzard actually cared and was more in touch with its fan-base.
9. Warcraft 3 + Frozen Throne - stellar games, until Blizzard-Activision destroyed them with a Reforged (Refunded) version that they seem to have abandoned in the mean time; luckily, I still own old copies of this game.
10. A Plague Tale: Innocence - a short, but truly rewarding story-based, stealth game, with a medieval setting; there is confirmation of a second installment and hopefully, this one will be longer and as good or even better than the first.