diff --git a/CMakeLists.txt b/CMakeLists.txt
index 294350e..a37a897 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,6 +15,7 @@ set(SOURCES
   src/display_engine.c
   src/mutation_engine.c
   src/mutation_data.c
+  src/epidemic_engine.c
   # ...
 )
 # Shared assets, fx-9860G-only assets and fx-CG-50-only assets
diff --git a/Plague.g1a b/Plague.g1a
index aaaa1f4..5e3df4a 100644
Binary files a/Plague.g1a and b/Plague.g1a differ
diff --git a/assets-fx/bground.png b/assets-fx/bground.png
index 3df997a..174080c 100644
Binary files a/assets-fx/bground.png and b/assets-fx/bground.png differ
diff --git a/assets-fx/plague.png b/assets-fx/plague.png
index 6c25191..2c3b91d 100644
Binary files a/assets-fx/plague.png and b/assets-fx/plague.png differ
diff --git a/src/core.c b/src/core.c
index d7f884c..c526a40 100644
--- a/src/core.c
+++ b/src/core.c
@@ -48,6 +48,9 @@ void next_frame(struct game *current_game)
         if (current_game->dna <= 100) current_game->dna += 1;
         current_game->time = 0;
 
+        current_game->research += current_game->priority;
+        // if (current_game->research > current_game->limit) ; game over
+
         // Epidemic propagation simulation to add here
     }
 }
diff --git a/src/core.h b/src/core.h
index d3eca8b..cd3f2dc 100644
--- a/src/core.h
+++ b/src/core.h
@@ -6,7 +6,7 @@
 #define CURSOR_TICK 150
 #define DNA_ANIMATION_TICK 150
 
-// The duration for DNA points and infectious model (ms)
+// Duration for DNA points and infectious model (ms)
 #define LIMIT_TICK 10000
 
 // Number of planes on screen
@@ -27,7 +27,7 @@ struct game
     int mutations_bought[3][14];
 
     // Research data
-    int research, limit;
+    int research, limit, priority;
 
     // Time
     int time;
diff --git a/src/display_engine.c b/src/display_engine.c
index 93379da..e9ee567 100644
--- a/src/display_engine.c
+++ b/src/display_engine.c
@@ -83,12 +83,13 @@ void display_mutation(const int table[4][8], const struct cursor c, const int mu
 }
 
 
-void display_mutation_buy(const struct cursor c, const int mutation_menu, const int table[4][8], const int button_selected)
+void display_mutation_buy(const struct cursor c, const int mutation_menu, const int table[4][8], const int button_selected, const struct game *current_game)
 {
     extern const bopti_image_t img_mutations;
     const int id = table[c.y][c.x];
 
     struct mutation *mutation_data = get_mutation_data(mutation_menu, id);
+    struct mutation *mutation_sel = get_mutation_data(mutation_menu, current_game->mutations_selected[mutation_menu]);
 
     dclear(C_WHITE);
     
@@ -97,9 +98,9 @@ void display_mutation_buy(const struct cursor c, const int mutation_menu, const
 
     dprint(47, 25, C_BLACK, mutation_data->name);
     dprint(81, 33, C_BLACK, "%d", mutation_data->dna);
-    dprint(81, 41, C_BLACK, "%d", mutation_data->contagion);
-    dprint(81, 49, C_BLACK, "%d", mutation_data->lethality);
-    dprint(81, 57, C_BLACK, "%d", mutation_data->severity);
+    dprint(81, 41, C_BLACK, "%d (%d)", mutation_data->contagion, mutation_data->contagion - mutation_sel->contagion);
+    dprint(81, 49, C_BLACK, "%d (%d)", mutation_data->severity, mutation_data->severity - mutation_sel->severity);
+    dprint(81, 57, C_BLACK, "%d (%d)", mutation_data->lethality, mutation_data->lethality - mutation_sel->lethality);
 
     if (button_selected) drect(81, 2, 123, 8, C_INVERT);
     else drect(81, 12, 123, 18, C_INVERT);
diff --git a/src/display_engine.h b/src/display_engine.h
index 6942f3c..916e4f8 100644
--- a/src/display_engine.h
+++ b/src/display_engine.h
@@ -13,7 +13,7 @@ void display_foreground(const int background, const struct game *current_game);
 void display_mutation(const int table[4][8], const struct cursor c, const int mutation_menu);
 
 // mutation_selected : display the mutation's informations screen
-void display_mutation_buy(const struct cursor c, const int mutation_menu, const int table[4][8], const int button_selected);
+void display_mutation_buy(const struct cursor c, const int mutation_menu, const int table[4][8], const int button_selected, const struct game *current_game);
 
 // output_error : display text and message background
 void display_message(const char *msg[5]);
diff --git a/src/epidemic_engine.c b/src/epidemic_engine.c
new file mode 100644
index 0000000..4caaf25
--- /dev/null
+++ b/src/epidemic_engine.c
@@ -0,0 +1,19 @@
+#include "epidemic_engine.h"
+
+int * count(const int epidemic_grid[10][20], int counter[4])
+{
+    for (int i = 0; i < 10; i ++)
+    {
+        for (int j = 0; j < 20; j ++)
+        {
+            counter[epidemic_grid[i][j]] ++;
+        }
+    }
+    return counter;
+}
+
+int can_become_infected(const int epidemic_grid[10][20], const int i, const int j)
+{
+    
+    return 0;
+}
\ No newline at end of file
diff --git a/src/epidemic_engine.h b/src/epidemic_engine.h
new file mode 100644
index 0000000..132d939
--- /dev/null
+++ b/src/epidemic_engine.h
@@ -0,0 +1,10 @@
+#ifndef _EPIDEMIC_ENGINE_H
+#define _EPIDEMIC_ENGINE_H
+
+// count : return an int *counter[4] of the form {healthy, infected, healed, dead}
+int * count(const int epidemic_grid[10][20], int counter[4]);
+
+// can_become_infected : return 0 if the case (i, j) isn't infectable, 1 else
+int can_become_infected(const int epidemic_grid[10][20], const int i, const int j);
+
+#endif /* _EPIDEMIC_ENGINE_H */
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index 2f9dbae..6e58790 100644
--- a/src/main.c
+++ b/src/main.c
@@ -15,6 +15,7 @@
 #include "core.h"
 #include "display_engine.h"
 #include "mutation_engine.h"
+#include "epidemic_engine.h"
 
 
 // title_screen : display the title screen
@@ -51,7 +52,8 @@ int main(void)
         .mutations_bought = {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}},
 
         .research = 0,
-        .limit = 100,
+        .limit = RESEARCH_LIMIT,
+        .priority = 0,
 
         .time = 0,
 
diff --git a/src/mutation_engine.c b/src/mutation_engine.c
index ed14116..8b0931a 100644
--- a/src/mutation_engine.c
+++ b/src/mutation_engine.c
@@ -96,7 +96,7 @@ int mutation_buy(struct game *current_game, const struct cursor c, const int mut
 
     while (1)
     {
-        display_mutation_buy(c, mutation_menu, table, button_selected);
+        display_mutation_buy(c, mutation_menu, table, button_selected, current_game);
         key = getkey().key;
 
         if (key == KEY_DOWN || key == KEY_UP) button_selected = (button_selected + 1) % 2;
@@ -149,9 +149,14 @@ void update_disease(struct game *current_game)
     struct mutation *ability = get_mutation_data(2, current_game->mutations_selected[1]);
     struct mutation *transmission = get_mutation_data(3, current_game->mutations_selected[2]);
 
+    // disease parameters
     current_game->contagion = symptom->contagion + ability->contagion + transmission->contagion;
     current_game->severity = symptom->severity + ability->severity + transmission->severity;
     current_game->lethality = symptom->lethality + ability->lethality + transmission->lethality;
+    
+    // research parameters
+    current_game->limit = RESEARCH_LIMIT + symptom->changement + ability->changement + transmission->changement;
+    current_game->priority = floor((symptom->severity + ability->severity + transmission->severity) / 10);
 }
 
 
diff --git a/src/mutation_engine.h b/src/mutation_engine.h
index 206ba50..b8d22d1 100644
--- a/src/mutation_engine.h
+++ b/src/mutation_engine.h
@@ -4,6 +4,9 @@
 #include "core.h"
 #include "display_engine.h"
 
+// Basic limit research
+#define RESEARCH_LIMIT 100
+
 // mutation_table : contain the map of the mutation available
 struct mutation_table
 {
@@ -39,5 +42,4 @@ struct mutation * get_mutation_data(const int mutation_menu, const int id);
 // init_mat : copy src into dest (for int)
 void init_mat(int x, int y, int dest[][x], int src[][x]);
 
-
 #endif /* _MUTATION_ENGINE_H */
\ No newline at end of file