How to make this lighting effect in HaxeFlixel or Unity?
How do I create this lighting effect in HaxeFlixel or Unity ?
I will tell you how it was created in this specific case. This question is very broad and there are very many ways to create lighting effects in both Unity and HaxeFlixel.
The image is of the game Beneath the City by Deepnight, accessible on his website. The game uses haxe although not with HaxeFlixel. It's deepnight's personal engine that works with the flash target. The source code is available here. The class where lighting takes place is in src/Level.hx and more specifically in the renderLights method. From what I gather, a light layer is layered above the sprites of the level. This layer (or bitmap data) has lights drawn as rectangles on it. This layer is then blurred, so that the lights don't appear as solid rectangles, but as faded blurs of spreading light. This takes place with flash blur filters. Blend modes are used to make the light Add in luminosity. A dark mask is then layered above the blur layer, presumably to prevent light in certain locations, such as in the fog of the game. (?). This all takes place between lines 208 and 248.
This game truly does have gorgous visuals, but the lighting goes beyond the initial blurred lights. Particles float around in the game that really add to the lightings aesthetic.
This is all how he does it though. How you do it is up to you. For HaxeFlixel, I would first consider alternatives such as this geometric lighting or this method of applying lighting to scenes, which looks closer to screenshot or even a very simple circle based lighting alternative. Searching Unity 2D lighting brings up plenty of options.
You've got plenty of options on how to approach the issue. I didn't answer this with a direct tutorial because the question isn't at the code level.