OpenProject's landing surface for a single user: work packages assigned to you, plus saved Gantt views. It queues by priority and date — there is no “what does this block?” ordering.
A3 and B2 are queued at the same rank as C1/D1 even though A3 is what unlocks the whole bring-up chain. Priority is a field you maintain by hand.
A blocker view is possible: filter on status Blocked, then read the predecessor column. It lists what is stuck, not what to finish first.
Stylised concept built from the project's public documentation and screenshots — not a pixel copy of the product, and not connected to any data.