Arena 90 and the Ghost Ladder
How the 90-node campaign, medal progress, and ranked ghosts turn practice into a visible progression loop.
Practice gets better when progress is visible. A flat list can be useful, but it does not give a learner much sense of where they are, what came before, or what kind of challenge is waiting next.
Arena 90 is our answer to that problem: a 90-node campaign path over real AlgoArena problems, paired with medals, unlocks, and ghost races so the work feels like a world instead of a spreadsheet.
What shipped
The campaign path is pinned to existing problem IDs. That matters. A campaign node should not drift every time the library changes order, and a learner should not open node 42 tomorrow to find a completely different concept by accident.
The current audit is intentionally concrete:
The medal model is partial-credit by design. Passing one case earns one medal. Passing at least half earns two. Passing every case earns three. That makes progress visible even when the learner has not fully solved the node yet.
Why ghosts belong here
Ghosts make empty lobbies feel less empty without pretending offline runs are live opponents. A player can race their own prior accepted attempt, or race an eligible human ghost when the run meets the replay bar.
That distinction matters. Self ghosts can be useful with looser rules because they only affect the person who created them. Human-pool ghosts need stricter eligibility: accepted and complete, clean practice or battle context, timed replay, enough events and snapshots, and no Rena, AI, hints, or imported context flags.
The result is a better ladder. You can practice alone, race a real historical attempt, or jump into live ranked when a match is available.
Why the route matters
The first Arena 90 map had the right idea but the wrong feel. Nodes were readable, but they sat on top of the map instead of belonging to it.
The product lesson is larger than a single art pass. Arena 90 needs the route, curriculum, unlock model, and illustration work to agree. The public contract starts with pinned nodes, coverage, prerequisites, medals, and replay eligibility; the map layer should be authored around that contract rather than used to disguise it.
That is the difference between "a UI over art" and "a campaign whose structure is visible."
What stays separate
Arena 90 attempts are clean-slate practice. Rena, AI, and hints stay disabled for the campaign route. That keeps medal progress and ghost eligibility understandable.
The goal is not to make practice harsher. It is to make the signal clearer. When a learner earns medals on a node, the product should know what that work represents.
Arena 90 is still a beginning, but it is now a beginning with a spine: a pinned path, visible progress, replayable targets, and a map that is starting to act like a world.