Låter som Timemaster från 1995. Från en online synopsis :
Den vise gamla mannen spelades av Pat Morita och IIRC de scener du har nämnt (honom erkänner att han är beroende av "blå", och läkemedlet läcker och blommar blommar) finns där. Trailern:The world has been destroyed by some sort of disaster, and the few remaining survivors are living in a "Mad Max" type of world, where they camp out in the ruins to defend themselves from raiders. [...] a group of aliens play games that affect the past, present, and future destiny of the universe. The aliens send "collectors" through space and time to planets where there are life forms to collect them as contestants or actually pawns for these virtual reality games, since the contestants really do not have free will over the outcomes. [...] The aliens bet on the outcome of these games with "blue", the distilled [liquid] substance of eternal life which is extracted from the losers of the game.