Couldn't limit to just top 5:
Fallout 4 - 364 hrs (was at 100% achievements until the Nuka-World DLC)
Borderlands 2 - 324 hrs
Endless Legend - 154 hrs
Star Trek Online - 139 hrs
Civilization V - 125 hrs
Binding of Isaac - 122 hrs
Borderlands - 105 hrs (+40 on PS3)
XCOM: Enemy Unknown - 95 hrs (+ 40 on PS3)
Doom 3: BFG Edition - 87 hrs (+ 80 at least since I had Doom 3 and RoE since they originally came out)
Honorable Mention: Half-Life 2 - 55 hrs, but I've been playing it since it came out, so add at least 100 to that for a few playthroughs.
PS: This doesn't count Mass Effect Trilogy (at least 120 hrs), or Blizzard games (Diablo, Diablo II + LoD, Diablo III + RoS, Warcraft III + FT, Starcraft + BW, Starcraft 2: WoL, HotS, LotV, Nova Missions + Co-op (probably 100 hrs just in co-op - and probably 2K+ hrs in Blizzard games over the years)). Or my consoles from Atari 2600 to PS3/Wii U.
Fallout 4 - 364 hrs (was at 100% achievements until the Nuka-World DLC)
Borderlands 2 - 324 hrs
Endless Legend - 154 hrs
Star Trek Online - 139 hrs
Civilization V - 125 hrs
Binding of Isaac - 122 hrs
Borderlands - 105 hrs (+40 on PS3)
XCOM: Enemy Unknown - 95 hrs (+ 40 on PS3)
Doom 3: BFG Edition - 87 hrs (+ 80 at least since I had Doom 3 and RoE since they originally came out)
Honorable Mention: Half-Life 2 - 55 hrs, but I've been playing it since it came out, so add at least 100 to that for a few playthroughs.
PS: This doesn't count Mass Effect Trilogy (at least 120 hrs), or Blizzard games (Diablo, Diablo II + LoD, Diablo III + RoS, Warcraft III + FT, Starcraft + BW, Starcraft 2: WoL, HotS, LotV, Nova Missions + Co-op (probably 100 hrs just in co-op - and probably 2K+ hrs in Blizzard games over the years)). Or my consoles from Atari 2600 to PS3/Wii U.