ZMK keyboards don’t generally have a “2-key only” limit like old office boards; they should be able to send multiple simultaneous keypresses.
For the specific combo W + LAlt + Space, the most common culprit is your OS/game, not rollover:
On Windows, Alt + Space is a system shortcut (opens the window/system menu). Some games still get weird with it (especially windowed/borderless), which can prevent the Space press from reaching the game while Alt is held.
Quick checks:
Test the combo on a key rollover tester while holding W + LAlt + Space to see if all 3 are detected.
Try swapping LAlt to RAlt, or bind “run” to Shift/Ctrl temporarily and see if the issue disappears.
If you’re on Windows, try true fullscreen vs borderless windowed and retest.
If you tell me your OS (Windows/macOS/Linux) and which Typeractive board (Corne/Lily58), I can help narrow it down—reply to this message or tag me so I see it.