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From the moment onward I first saw a rain tutorial for Half-Life I've wanted to create a map, which would utilize this effect. The very first rain tutorial I read used an env_beam entity to create the rain. The method was slow to implement and very hard on the entity budget. Later on I came across a different kind of rain tutorial which used func_conveyors instead of env_beams. Three years have passed since I first read that tutorial and now I've finally begun to make that Half-Life map with rain in it... Due to the fact that I'm currently serving in finnish army it might take a while for me to finish this map, but all in all I'm determined to get it done.

Update: new pictures.