Zounds! is a free game system distributed as a PDF. It is rules light, so should be easy to learn.
I will summarize the rules here & on the character creation page. But I recommend you read the main PDF (at least the 2/3 of it that isn’t meant for GMs).
In Zounds there is one primary rule: does this proposed action make sense in the game world?
Players describe something that they want to have happen (their action or just something happening in the world). If it makes sense according to the primary rule and no one else at the table disagrees with it happening, it happens. It may not have the desired result, but it happens. Dice come into play when we want to see what effect something had, or when someone thinks the drama / fun will be larger if there is a chance that this thing fails.
Roll for effect
Zounds! is a roll for effect system. This means that the roll does not determine whether something happens. If a player or DM described it, it happens. The question is what effect will result from the action.
The effect of any given action is resolved by a single roll. The roll determines the system effect (nothing, hindered, out, overkill). We then interpret that result in the game world.
In order to keep the action fast and cinematic, there are a couple of tropes that anyone at the table can use. These are the fade to black and the cut away.
Fade to black is used whenever some scene is starting to drag out. Anyone can simply narrate how the camera is fading to black, focusing in on something and blurring out, or some similar effect. If no one interrupts, the scene ends.
If anyone has anything they absolutely must do before fading, they can interrupt and describe what happens. But after a fade to black is called, the group should try to wrap things up quickly and fade out so that they can get to the next interesting scene rather than spending an hour fiddling around at the potion shop.
Cut aways are used whenever we either have simultaneous action at separate locations or we need some flashback. They can be called by anyone, but will most often be used by the GM.
Feel free to use them if you really need some characterization. There will also be some powers that trigger cut scenes (things of the “good thing I happened to plan for just this occasion” nature).
Try to keep cut aways from interrupting the flow. Wait until the end of an action or set of actions. People generally shouldn’t interrupt cut aways—we will be back to this scene as soon as we get done with the cut scene.
The main thing is to keep the mood right. Don’t cut away from action to a long exposition. Don’t cut away from a deep drama to a comedy show. If you’re going to cut away for a flashback, keep it short and to the point. The best cut scenes are still-life images or a few seconds of action that make real-time actions suddenly make sense.
To execute a cut away, simply describe how the camera cuts away to the other scene. Use visual description in your transitions. Cut aways to parallel action will often look a lot like fading to black and then entering the new scene; I’ll choose some transition that fits the mood.