I'll go into more detail about the UI.
Overall the art resembles something from the 90's, which could be ok if it is intended, but aesthetically you break alot of design principles overall.
- Over 50% of the first screen is a low-res border, which is not a good thing.
- The button seems out of place, and does not fit the theme you're after. - When interacting with the button, there is no visual feedback. An easy and common way around this is to change the sprite/light it up when the mouse is hovering over it.
On the second screen there is also a few points.
- I am presented with a screen with an overload of information, which visually asks for my interaction. I have on the other hand no idea what the game is about, and definitely not what the consequences of my actions here will be.
- The overall color palette is way off, with alot of different colors. With a pop-up visible, i can see at least 10 different colors. You only need a few, and in my example below i can show u my GUI, which uses 1 single base color.
- Some of the pop-up windows have a close button, and some dont. This is breaking the flow in the design.
The character customization screen is ok, but it still resembles the same UI flaws as described above.
In-game it is a mess, with text hovering everywhere, inconsistent art and barely visible vital elements.
- The weapons are barely visible, because of its background on the icons.
- The pause and the options button is not centered, and its placement is not ideal.
- The colors of the text visible (for example equipped weapons) is white, and on top of a light background it does not fit in well.
- There is also alot of information on the screen which doesnt make any sense for the player.
Apart from the crazy AI which runs immensely fast all over and one-shots you, you seem to have a lot of base and potential on the technical side. For it to be a good game you must think of the presentation of it, and an art revision (or help from an artist) would really lift the game. The GUI and HUD also needs alot of work. Its all about wrapping it together, with a coherent look.
Think of the player/consumer, and how they will perceive the game. In its current state i would most likely reject this game upon seeing the first screens, if i were to find this game on the web.
Here is some examples of the UI i recently made for my project.
<img src="http://bildr.no/image/1209927.jpeg" border="0">
Image 1
<img src="http://bildr.no/image/1209928.jpeg" border="0">
Image 2
<img src="http://bildr.no/image/1209929.jpeg" border="0">
Image 3
I'm not saying my UI is perfect, and it most likely wouldnt fit your game with that style, but its tidy and somewhat correct, and illustrates how you can create a UI with 1-2 base colors.