Open with ⌘Space

One switch in Settings.

Open Settings… from the menu bar and turn on Use ⌘Space in place of Spotlight. Superhound turns off Spotlight’s ⌘Space shortcut and takes ⌘Space.

To give ⌘Space back to Spotlight, turn the switch off. Superhound then moves to ⌥Space, or keeps its keys when ⌥Space is in use. You can also pick another shortcut in Settings….

Superhound 0.2.0 and earlier have no switch. There, turn off Show Spotlight search in System Settings → Keyboard → Keyboard Shortcuts → Spotlight.