diff --git a/Plague.g1a b/Plague.g1a
index bfc6a57..031f2e3 100644
Binary files a/Plague.g1a and b/Plague.g1a differ
diff --git a/src/core.c b/src/core.c
index 3be605c..a476971 100644
--- a/src/core.c
+++ b/src/core.c
@@ -1,6 +1,7 @@
 #include <gint/timer.h>
 #include <gint/clock.h>
 #include <gint/keyboard.h>
+#include <math.h>
 
 #include "core.h"
 #include "mutation_engine.h"
@@ -53,12 +54,12 @@ void next_frame(struct game *current_game)
         current_game->time = 0;
 
         // Update the game
-        if (current_game->dna <= 100) current_game->dna += 1;
-        current_game->research += current_game->priority;
+        if (current_game->dna <= 100) current_game->dna += 1 + floor(current_game->severity / 25);
+        if (current_game->research < current_game->limit) current_game->research += current_game->priority;
         epidemic_simulation(current_game);
 
         // Check the end of the game
-        if (current_game->research > current_game->limit)
+        if (current_game->research >= current_game->limit)
         {
             const char *msg[5] = {"Vous avez", "perdu.", "", "", ""};
             message(msg);
diff --git a/src/mutation_engine.c b/src/mutation_engine.c
index 403257f..1fa3c1d 100644
--- a/src/mutation_engine.c
+++ b/src/mutation_engine.c
@@ -158,7 +158,7 @@ void update_disease(struct game *current_game)
     
     // research parameters
     current_game->limit = RESEARCH_LIMIT + symptom->changement + ability->changement + transmission->changement;
-    current_game->priority = floor((current_game->severity + current_game->lethality) / 200);
+    current_game->priority = floor((current_game->severity + current_game->lethality) / 40);
 }