The third ingame video shows off a brief look at some puzzle elements in the game. With a mix-match of different environments. Let us also take a look at one specific gameplay feature.
1x, 2x, 3x, 4x - As seen in the gameplay videos and screenshots there is a multiplier number next to the stamina meter. This is a score multiplier that is based on killing enemies, similar to a kill streak system. For each enemy you kill the multiplier is added with one, up to the maximum of 4x. The multiplier adds up on all points you recieve or collect, from enemies and coins. Each level also gives the player a greater damage dealt from the weapon of use. This is extra useful when you encounter enemies such as the giant brainwashed civilian as he is tougher and will reward you with more points than other enemies. At level 4 you receive a small health bonus for each enemy you kill. This is a simple but fun way of making firefights more interesting as well as encouraging players to go full on guns blazing when encountering mobs.
Here's the gameplay video, and as always, everything is still work in progress: