day and nite

is there a way using dynamic lighting to make it so it just  makes it harder to see? like nighttime or dark shadows? and when players move with thier lightsource they see better?

Several ways, depending on what you want to achieve. You can place a token that produces very dim light (adjust with the slider) over a huge area. If you are using DL blocking walls, you might need to place several and adjust for overall brightness. You can use Explorer Mode and pre-reveal the map by dragging their characters all over it. This will limit their vision to what they can currently see, but they will have a dimmed out overview of the entire map. You can use an invisible token with a huge dark aura that covers the play area. This will darken the table, but won't really affect vision settings. Whatever you decide to try, I would strongly suggest testing with a  Dummy Account . Ctrl-L is a terribly guide for checking lighting seetups.

You could just assign every character Nightvision in those low-light maps. The quickest way to do this is with the TokenMod API. I use a macro that calls TokenMod, and lets me select the party, and with two clicks assign everyone vision appropriate to the situation: 90 ft nightvision for full moon, 60 ft nightvision for half-moon, 0 nightvision for utter darkness, no vision of any kind for blindness, etc. etc. I may be wrong about this, but I don't THINK that TokenMod can affect the "Dimming" property for UDL Nightvision yet. Which is unfortunate, because it means that the Nightvision is all very bright unless you add "Dimming" manually for each token. I assume this property will be added as UDL is finalized. In the meantime, I use the brute force method of stretching a semi-transparent black graphic over the map layer. (If I'm lucky, I'm misreading the TokenMod Help menu and someone will let me know!)

Ach, you're right. The slider is for nightvision, not light. And that would be an excellent way to handle it. In the Rime of the Frost Maiden campaign we are playing we have an outdoor city map with no blockers, where building doors have lamps of low light vision, creating pools of light all over the map. Really gets the feeling across.