popn: distinguish between hpm and new popn (#619)

## Link to GitHub Issue or related Pull Request, if one exists
#618

## Description of change
Enhance game detection logic.

Fix heap size.

src/spice2x/games/popn/popn.h

@@ -1,9 +1,14 @@
 #pragma once
 
+#include "avs/game.h"
 #include "games/game.h"
 
 namespace games::popn {
 
+    static inline bool is_pikapika_model() {
+        return (avs::game::is_model("M39") && avs::game::SPEC[0] == 'D');
+    }
+
     class POPNGame : public games::Game {
     public:
         POPNGame();