Glowing ones and several arrows to tell where the target is.
lol.
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Seriously, I find this very useless. First, because as I said in the other thread, the most important for reflexes is not color or bright models but movements, and there are already some cvars that fulfill the needs.
Secondly, you can use r_gamma and r_intensity to see the game better (and even without brightskin, you get to see more than enough).
Thirdly, there are already some brightskins packages, so you can add it on your server and with sv_pure force everyone to dl it. At least servers admins get the choice to include or not brightskins depending on their idea about the question. Or you can use a mod with customizable brightskin color like ExcessivePlus.
Fourth, there is a fork which is mainly aimed at bringing brightskins :
http://www.evilarena.de/development/----------------
If brightskins are ever implemented into the game, servers admins should be able to allow or disallow it.