diff --git a/core/src/Scoreboard.cpp b/core/src/Scoreboard.cpp
new file mode 100644
index 0000000..57af12f
--- /dev/null
+++ b/core/src/Scoreboard.cpp
@@ -0,0 +1,153 @@
+#include "vf/Scoreboard.h"
+
+#include <algorithm>
+
+namespace vf {
+
+namespace {
+
+int clampToScore(long long value) {
+    const long long high = 2147483647ll;
+    const long long low = -2147483648ll;
+    if (value > high) return static_cast<int>(high);
+    if (value < low) return static_cast<int>(low);
+    return static_cast<int>(value);
+}
+
+std::string twoDigits(long long value) {
+    std::string text = std::to_string(value);
+    return text.size() < 2u ? "0" + text : text;
+}
+
+} // namespace
+
+const char* statKindName(StatKind kind) {
+    switch (kind) {
+        case StatKind::DistanceWalked: return "distanceWalked";
+        case StatKind::DistanceSprinted: return "distanceSprinted";
+        case StatKind::DistanceSwum: return "distanceSwum";
+        case StatKind::DistanceFallen: return "distanceFallen";
+        case StatKind::DistanceClimbed: return "distanceClimbed";
+        case StatKind::BlocksBroken: return "blocksBroken";
+        case StatKind::ItemsUsed: return "itemsUsed";
+        case StatKind::MobsKilled: return "mobsKilled";
+        case StatKind::Deaths: return "deaths";
+        case StatKind::DamageDealt: return "damageDealt";
+        case StatKind::DamageTaken: return "damageTaken";
+        case StatKind::PlayTicks: return "playTicks";
+        case StatKind::Count: break;
+    }
+    return "unknown";
+}
+
+bool parseStatKindName(const std::string& text, StatKind& out) {
+    for (int i = 0; i < static_cast<int>(StatKind::Count); ++i) {
+        StatKind kind = static_cast<StatKind>(i);
+        if (text == statKindName(kind)) {
+            out = kind;
+            return true;
+        }
+    }
+    return false;
+}
+
+bool statKindHasSubject(StatKind kind) {
+    return kind == StatKind::BlocksBroken || kind == StatKind::ItemsUsed ||
+           kind == StatKind::MobsKilled;
+}
+
+bool statKindIsDistance(StatKind kind) {
+    return kind == StatKind::DistanceWalked || kind == StatKind::DistanceSprinted ||
+           kind == StatKind::DistanceSwum || kind == StatKind::DistanceFallen ||
+           kind == StatKind::DistanceClimbed;
+}
+
+void StatSheet::add(StatKind kind, long long amount) { addFor(kind, 0, amount); }
+
+void StatSheet::addFor(StatKind kind, int subject, long long amount) {
+    if (amount == 0) return;
+    cells[std::make_pair(kind, subject)] += amount;
+    ++changes;
+}
+
+void StatSheet::addBlockBroken(Block block, long long amount) {
+    addFor(StatKind::BlocksBroken, static_cast<int>(block), amount);
+}
+
+void StatSheet::addItemUsed(ItemId item, long long amount) {
+    addFor(StatKind::ItemsUsed, static_cast<int>(item), amount);
+}
+
+void StatSheet::addMobKilled(Species species, long long amount) {
+    addFor(StatKind::MobsKilled, static_cast<int>(species), amount);
+}
+
+void StatSheet::clear() {
+    if (cells.empty()) return;
+    cells.clear();
+    ++changes;
+}
+
+long long StatSheet::total(StatKind kind) const {
+    long long sum = 0;
+    for (const auto& cell : cells)
+        if (cell.first.first == kind) sum += cell.second;
+    return sum;
+}
+
+long long StatSheet::value(StatKind kind, int subject) const {
+    auto found = cells.find(std::make_pair(kind, subject));
+    return found == cells.end() ? 0 : found->second;
+}
+
+long long StatSheet::blocksBroken(Block block) const {
+    return value(StatKind::BlocksBroken, static_cast<int>(block));
+}
+
+long long StatSheet::itemsUsed(ItemId item) const {
+    return value(StatKind::ItemsUsed, static_cast<int>(item));
+}
+
+long long StatSheet::mobsKilled(Species species) const {
+    return value(StatKind::MobsKilled, static_cast<int>(species));
+}
+
+long long StatSheet::distanceTravelled() const {
+    long long sum = 0;
+    for (int i = 0; i < static_cast<int>(StatKind::Count); ++i) {
+        StatKind kind = static_cast<StatKind>(i);
+        if (statKindIsDistance(kind)) sum += total(kind);
+    }
+    return sum;
+}
+
+std::vector<StatCounter> StatSheet::counters() const {
+    std::vector<StatCounter> out;
+    out.reserve(cells.size());
+    for (const auto& cell : cells) {
+        StatCounter counter;
+        counter.kind = cell.first.first;
+        counter.subject = cell.first.second;
+        counter.value = cell.second;
+        out.push_back(counter);
+    }
+    return out;
+}
+
+int StatSheet::distinctSubjects(StatKind kind) const {
+    int count = 0;
+    for (const auto& cell : cells)
+        if (cell.first.first == kind) ++count;
+    return count;
+}
+
+const char* displaySlotName(DisplaySlot slot) {
+    switch (slot) {
+        case DisplaySlot::PlayerList: return "playerList";
+        case DisplaySlot::Sidebar: return "sidebar";
+        case DisplaySlot::BelowName: return "belowName";
+        case DisplaySlot::Count: break;
+    }
+    return "unknown";
+}
+