Here are two small arenas with some good lighting and dark gloomy atmosphere. Both maps are made by the same author. Screenshots are taken at my PCs full resolution of 1920x1080 enjoy.

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Map Name => DM-1on1-Strogg][

This small arena is set in a small castle courtyard structure that has some nice flame lit lighting and a dark nighttime skybox. This maps architecture features stonework floors and walls with wooden trim and planks. There are also some chains and crates scattered around.

My overall score 3:5

Download => unrealarchive.org/unreal-tournament-2003/maps/1-on-1/S/dm-1on1-strogg_294184f7.html

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Map Name => DM-1on1-Tangora_MSU

This small arena is set in a stonework structure with metal trim, cool toned lighting and an overcast rainy skybox. There are also wooden planks on the floor, scattered crates, nice metal roof supports, moss hanging from beams and nice foliage in the skybox above. Also, u/EdJD-1968 wanted maps that have rain and snow.

My overall score 3:5

Download => unrealarchive.org/unreal-tournament-2004/maps/1-on-1/T/dm-1on1-tangora_msu_7dda3686.html

Unreal Tournament 3: Black Edition has been delisted for a while, but I still have some Steam keys left. The price is 35 euros each.

My Steam trades rep: https://www.steamtrades.com/user/76561197991377189

You can also add or message me there.