diff --git a/README.md b/README.md
new file mode 100644
index 0000000..893187c
--- /dev/null
+++ b/README.md
@@ -0,0 +1,10 @@
+# Conway's Game Of Life
+
+An implementation in C.
+
+Usage: ./life [GRID SIZE=20] [WAIT BETWEEN EACH STEP=4] [MAX STEP=-1]
+
+WAIT is written as 1e6 / WAIT, which we wait as a fraction of a second.
+
+I will one day write a good frontend for the CLI, along with proper
+logging, and readin and readout of RLE, and maybe more.
diff --git a/life.c b/life.c
index eb84346..35ed216 100644
--- a/life.c
+++ b/life.c
@@ -9,6 +9,25 @@
 #include <time.h>
 #include <unistd.h>
 
+/* defaults */
+
+#define DEFAULT_GRID_SIZE "20"
+#define DEFAULT_WAIT 4
+#define DEFAULT_MAX_STEP -1
+
+/* symbols used */
+
+char symbol [] = " O.";
+
+/* ... */
+
+/* maps to symbol */
+enum {
+  LIFE_NONE,
+  LIFE_ALIVE,
+  LIFE_DEAD
+};
+
 #define DELC static inline
 
 /* nearness mask, life mask */
@@ -17,14 +36,6 @@
 /* life nearness function */
 #define life_near life_near_lim
 
-enum {
-  LIFE_NONE,
-  LIFE_ALIVE,
-  LIFE_DEAD
-};
-
-char symbol [] = " O.";
-
 /* tty */
 
 #define CSI "\033["
@@ -229,18 +240,19 @@ int main (int argc, char ** argv) {
   if ( argc >= 2
   &&  (strcmp (argv [1], "-h") == 0
   ||   strcmp (argv [1], "--help") == 0)) {
-    printf ("%s [GRID SIZE] [WAIT BETWEEN EACH STEP=4] [MAX STEP=-1]\n", argv [0]);
+    printf ("%s [GRID SIZE=%s] [WAIT BETWEEN EACH STEP=%d] [MAX STEP=-%d]\n",
+	    argv [0], DEFAULT_GRID_SIZE, DEFAULT_WAIT, DEFAULT_MAX_STEP);
     return 1;
   }
 
-  char * rect = argc >= 2 ? argv [1] : "20";
+  char * rect = argc >= 2 ? argv [1] : DEFAULT_GRID_SIZE;
   board_t * b = board_alloc_text (rect);
 
   board_randomize (b, 5);
   board_eq_filter (b, 1);
 
-  int wait = argc >= 3 ? atoi (argv [2]) : 4;
-  int step = argc >= 4 ? atoi (argv [3]) : -1;
+  int wait = argc >= 3 ? atoi (argv [2]) : DEFAULT_WAIT;
+  int step = argc >= 4 ? atoi (argv [3]) : DEFAULT_MAX_STEP;
 
 #ifndef NDEBUG
   life_debug_near (b, 0, 0);