I don't have a tutorial but I will try to explain the way I make rain effects.

- Pick 2 blue colors. (A dark blue and a light blue)

- Pick another color that has blue in it. (I use the darkest or lightest color in my grass tiles)

- Make lines of different length using the three colors you chose.(What I do here is.. I don't make the lines touch the bottom. That way when the tiles are put together they don't continuely run.)

- Copy and paste what you have made into Dream Maker(if its not in it already).

- Pick one of the colors and change the Alpha to around 100-150. (You can change this depending on what number you feel best) Swap the non-alpha color with the alpha color. Repeat for the other colors.

- Copy the image and paste it into a new frame.

- Using the select tool select your entire area where you pixeled. (As I mentioned above I don't make the lines go to the bottom so I would only select to the most bottom pixel and I would change it with the frames to make the rain drop in different spots.)

- Use the down arrow to pull the selected area down. (The more you pull it down the faster the rain will appear to fall and makes it look less smooth. I pull it down about 4 pixels.)

- Repeat copying and pasting the work into the next frame until the animation looks smooth.

- Now you have a nice smooth falling rain. Add in little splash effects to the falling rain to give it alittle more uniqueness.

For the part of making it not look like just repeated patterns...

This would be a coders job. Theres always gonna be a pattern when you pixel a looped animation. Best way is to make multiple rain animations and make the coder change the icon_states at random intervals.

Here's a gif of rain I saved awhile back when I was thinking of creating some weather effects.



The impact is just as important as the lines caused by falling rain. Without the impact the rain looks very flat.