# Tune the difficulty curve

Request: `$ARGUMENTS`

The whole slope of the game lives in one place: `projects/<project>/project.txt`. The shape
of the curve is code (`engine/progression.cpp`), its coefficients are data. Read
`docs/16-descent.md` for what each number means and why it is shaped that way.

## Measure before changing

```bash
tile2d_editor --tool curve 1 20          # what depth means today, floor by floor
tile2d_editor --tool floor <depth> 1     # one floor: budget spent, population, loot
tile2d_editor --tool floor <depth> 42    # same depth, another seed — variance matters
```

Change one line of `project.txt`, run the same commands, and compare. A tuning change with
no before/after numbers is an opinion.

## What the numbers are for

| key | meaning | the trap |
|---|---|---|
| `danger` | base, linear growth, quadratic tail | pure linear reads as "same, but more"; pure exponential ends the run where the player just started understanding the rules |
| `density` | how often spawn points fire, and the cap | above the cap every point always fires, so floors stop differing |
| `loot` | drops and how fast tier climbs | tier must lag danger, or the squad is dressed for the rest of the game by floor ten |
| `sight` | how fast vision shrinks, and the floor | below the floor it stops being frightening and becomes "can't see where to go" |
| `xp` | experience multiplier per floor | must grow slower than danger, or skipping floors becomes the only sane play |
| `themes` | where each finish band starts | must ascend; the last band is open-ended on purpose |

Do **not** add creature HP or damage multipliers to make depth harder. "The same shambler
with triple HP" is not scarier, it is longer. Depth changes *who* comes out and how many.

## Verify

```bash
tile2d_editor --tool validate            # set still covers the depths you moved
squad_proto --project <name> --descend 8 # the curve survives an actual run
```

Watch for `ЗАМЕЧАНИЕ` in validate: the floor assembled correctly but the room set no longer
keeps up with the curve. That means "draw more rooms", not "lower the curve" — unless the
curve is what you were asked to change.

## Report

The exact lines you changed, and the `curve` table before and after for the depths that
matter. Name the floors where behaviour changed most.