Risk Register Heat Matrix (Vega-Lite)

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "title": "Open risk register - inherent likelihood by impact (count of risks)",
  "data": {
    "values": [
      {"likelihood": "Rare", "impact": "Severe", "n": 3, "score": 4},
      {"likelihood": "Unlikely", "impact": "Severe", "n": 5, "score": 8},
      {"likelihood": "Possible", "impact": "Severe", "n": 4, "score": 12},
      {"likelihood": "Likely", "impact": "Severe", "n": 2, "score": 16},
      {"likelihood": "Rare", "impact": "Major", "n": 6, "score": 3},
      {"likelihood": "Unlikely", "impact": "Major", "n": 11, "score": 6},
      {"likelihood": "Possible", "impact": "Major", "n": 9, "score": 9},
      {"likelihood": "Likely", "impact": "Major", "n": 4, "score": 12},
      {"likelihood": "Rare", "impact": "Moderate", "n": 8, "score": 2},
      {"likelihood": "Unlikely", "impact": "Moderate", "n": 17, "score": 4},
      {"likelihood": "Possible", "impact": "Moderate", "n": 21, "score": 6},
      {"likelihood": "Likely", "impact": "Moderate", "n": 7, "score": 8},
      {"likelihood": "Rare", "impact": "Minor", "n": 4, "score": 1},
      {"likelihood": "Unlikely", "impact": "Minor", "n": 12, "score": 2},
      {"likelihood": "Possible", "impact": "Minor", "n": 15, "score": 3},
      {"likelihood": "Likely", "impact": "Minor", "n": 10, "score": 4}
    ]
  },
  "encoding": {
    "x": {"field": "likelihood", "type": "ordinal", "sort": ["Rare", "Unlikely", "Possible", "Likely"], "title": "Likelihood"},
    "y": {"field": "impact", "type": "ordinal", "sort": ["Severe", "Major", "Moderate", "Minor"], "title": "Impact"}
  },
  "layer": [
    {
      "mark": {"type": "rect", "stroke": "#ffffff", "strokeWidth": 2},
      "encoding": {"color": {"field": "score", "type": "quantitative", "scale": {"scheme": "orangered"}, "title": "Risk score"}}
    },
    {
      "mark": {"type": "text", "fontSize": 14, "fontWeight": "bold"},
      "encoding": {"text": {"field": "n", "type": "quantitative"}, "color": {"value": "#0f172a"}}
    }
  ]
}