First cut of pulling out the relevant parts of my original game to make a little framework.

src/gui/debug_ui.cpp

@@ -0,0 +1,102 @@
+#include "gui/debug_ui.hpp"
+#include "constants.hpp"
+#include "events.hpp"
+#include <optional>
+#include <fmt/core.h>
+#include <fmt/xchar.h>
+#include "game/components.hpp"
+
+namespace gui {
+  using namespace guecs;
+
+  void DebugUI::init(lel::Cell cell) {
+    $gui.position(cell.x, cell.y, cell.w, cell.h);
+    $gui.layout(
+        "[*%(100,400)debug_text]"
+        "[_]"
+        "[_]"
+        "[_]"
+        "[spawn1|spawn2|spawn3]"
+        "[spawn4|spawn5|spawn6]");
+
+    add_spawn_button("RAT_GIANT", "rat_with_sword", "spawn4");
+
+    $gui.init();
+  }
+
+  void DebugUI::add_spawn_button(std::string enemy_key, std::string sprite_name, std::string region) {
+    auto button = $gui.entity(region);
+    $gui.set<guecs::Clickable>(button, {
+        [this, enemy_key](auto){ spawn(enemy_key); }
+    });
+    $gui.set<guecs::Sprite>(button, { sprite_name});
+  }
+
+  void DebugUI::spawn(const std::string& enemy_key) {
+    (void)enemy_key;
+    dbc::log("THIS FUNCTION NEEDS A REWRITE");
+    // auto ent = $level_mgr.spawn_enemy(enemy_key);
+    // auto& level = $level_mgr.current();
+    // level.world->send<game::Event>(game::Event::ENTITY_SPAWN, ent, {});
+  }
+
+  void DebugUI::render(sf::RenderWindow& window) {
+    if(active) {
+      auto& level = GameDB::current_level();
+      auto player = level.world->get_the<components::Player>();
+      auto player_combat = level.world->get<components::Combat>(player.entity);
+      auto map = level.map;
+
+      std::wstring stats = $F(L"STATS\n"
+          L"HP: {}\n"
+          L"mean:{:>8.5}\n"
+          L"sdev: {:>8.5}\n"
+          L"min: {:>8.5}\n"
+          L"max: {:>8.5}\n"
+          L"count:{:<10}\n"
+          L"level: {} size: {}x{}\n\n"
+          L"VSync? {}\n"
+          L"FR Limit: {}\n"
+          L"Debug? {}\n\n",
+          player_combat.hp, $stats.mean(), $stats.stddev(), $stats.min,
+          $stats.max, $stats.n, level.index, map->width(), map->height(),
+          VSYNC, FRAME_LIMIT, DEBUG_BUILD);
+
+      $gui.show_text("debug_text", stats);
+      $gui.render(window);
+      // $gui.debug_layout(window);
+    }
+  }
+
+  void DebugUI::debug() {
+    active = !active;
+
+    if(active) {
+      auto& level = GameDB::current_level();
+      // it's on now, enable things
+      auto player = level.world->get_the<components::Player>();
+      auto& player_combat = level.world->get<components::Combat>(player.entity);
+      player_combat.hp = player_combat.max_hp;
+      $gui.show_text("debug_text", L"STATS");
+    } else {
+      // it's off now, close it
+      $gui.close<Text>("debug_text");
+    }
+  }
+
+  bool DebugUI::mouse(float x, float y, guecs::Modifiers mods) {
+    return $gui.mouse(x, y, mods);
+  }
+
+  Stats::TimeBullshit DebugUI::time_start() {
+    return $stats.time_start();
+  }
+
+  void DebugUI::sample_time(Stats::TimeBullshit start) {
+    $stats.sample_time(start);
+  }
+
+  void DebugUI::reset_stats() {
+    $stats.reset();
+  }
+}