Source: Steam Community (opens in a new tab)

Movement type and detection
It affects the speed of movement, its cost and noise generation.
There are three modes:
- Walk- standard values.
- Sneaky - 50% more cost of action points, 50% less noise generation and chance of visual detection. The opponent has a better chance of reacting on a player's turn.
- Run - 50% less cost of action points, 50% more noise generation and chance of visual detection. The opponent has less chance of reacting on a player's turn.