Abstract is a toy sandbox-style game where you can connect different types of vertices with different effects to form complex graphs. It is currently in alpha-level quality, so don't expect too much.
The rules of the game are that you can connect vertices by arcs (i.e arrows, or directed connections) or by edges (undirected connections). Arcs can transmit a numeric value. Edges enforce their length (currently unimplemented). The vertices themselves can have different effects, as described below.
The controls are similar to Minecraft.
Place a vertex by selecting the vertex type you want to use and right-clicking on an empty part of the world. If the vertex is a switch, you can right-click on it to toggle its state. Move vertices by left clicking and dragging them. Left click a vertex to delete it.
Connect two vertices by selecting what type of connection you want to use, holding right click on the starting vertex, and releasing it on the ending vertex.
Left click and drag on an empty part of the world to pan around. Select multiple vertices by holding down the Ctrl key while left-dragging. You can press the Delete key to remove them.
T key: Shows in-game tutorial, in case you forgot something.
S key: Save the world manually.
C key: Toggle autosaving. Default is on.
Z key: Use arc connections.
X key: Use edge connections.
Degree: Displays the degree of the vertex (how many edges, not arcs) it has. It also outputs this information as a numerical value via arcs.
Anchor: The position of this vertex in the world is fixed, and cannot be moved by mouse, other vertices, or any unstoppable forces (untested).
Meter: Shows the value of the sum of its inputs. Re-transmits its input.
Switch: Can be in an off or on state. On state outputs positive one to all neighbors. Off state outputs negative one. Default state is off.
Min: The numerical equivalent of a boolean AND gate. Outputs the smallest number it receives as input. If there are no inputs, it returns positive infinity.
Max: The numerical equivalent of a boolean OR gate. Outputs the largest number it receives as input. If there are no inputs, it returns negative infinity.
Negate: The numerical equivalent of a trinary NOT gate. Takes the biggest input, negates it, and outputs it. If there are no inputs, it outputs positive infinity.
Neuron: Only sends a signal when the inputs surpass a certain threshold. Current threshold is 3.
Sensor: Gives a value from 0 to 1 of how close the closest vertex is. Detection ends at 0, which is 240 pixels away.
Rotator: Rotates neighbors connected by edge when receiving a non-zero input signal. Negative values rotate counter-clockwise, positive values rotate clockwise. Currently doesn't rotate in a perfect circle.