diff --git a/src/gohamster.pas b/src/gohamster.pas
index 3dda1e3..a3e4d8a 100644
--- a/src/gohamster.pas
+++ b/src/gohamster.pas
@@ -1,5 +1,110 @@
 program go_hamster;
 
+uses crt;
+
+const
+      FieldSize = 82;
+      InterfaceHeight = 14;
+      MinScreenH = FieldSize;
+      WidthCoefficient = 2;
+      MinScreenW = FieldSize * WidthCoefficient;
+      FieldBorder = '#';
+      BorderWidth = 2;
+      DelaySizeMs = 50;
+      EscCode = 27;
+      CtrlCCode = 3;
+
+function IsScreenValid: boolean;
 begin
-    writeln('Repo init')
+    IsScreenValid :=
+        (ScreenWidth >= MinScreenW) and (ScreenHeight >= MinScreenH)
+end;
+
+procedure PrintScreenHelp;
+begin
+    writeln('Increase your screen size and try again.');
+    if ScreenWidth < MinScreenW then
+    begin
+        writeln('Your screen width: ', ScreenWidth,
+                '. Required: ', MinScreenW, '.')
+    end;
+    if ScreenHeight < MinScreenH then
+    begin
+        writeln('Your screen height: ', ScreenHeight,
+                '. Required: ', MinScreenH, '.')
+    end
+end;
+
+procedure GetKey(var code: integer);
+var
+    c: char;
+begin
+    c := ReadKey;
+    if c = #0 then
+    begin
+        c := ReadKey;
+        code := -ord(c)
+    end
+    else
+    begin
+        code := ord(c)
+    end
+end;
+
+procedure DrawLine(x, y, len: integer);
+var
+    i: integer;
+begin
+    GotoXY(x, y);
+    for i := 1 to len do
+        write(FieldBorder);
+    GotoXY(1, 1)
+end;
+
+procedure DrawInterface;
+begin
+    DrawLine(1, InterfaceHeight, FieldSize * WidthCoefficient)
+end;
+
+procedure DrawField(x0, y0, size: integer);
+var
+    i: integer;
+begin
+    clrscr;
+    DrawLine(x0, y0, size * WidthCoefficient);
+    for i := 1 to size - 2 do
+    begin
+        GotoXY(x0, y0 + i);
+        write(FieldBorder);
+        GotoXY(x0 + size * WidthCoefficient - 1, y0 + i);
+        write(FieldBorder)
+    end;
+    DrawLine(x0, y0 + size - 1, size * WidthCoefficient);
+    GotoXY(1, 1);
+    DrawInterface
+end;
+
+
+var
+    code: integer;
+begin
+
+    if not IsScreenValid then
+    begin
+        PrintScreenHelp;
+        exit
+    end;
+    DrawField(1, 1, FieldSize);
+    while true do
+    begin
+        delay(DelaySizeMs);
+        if keypressed then
+        begin
+            GetKey(code);
+            writeln(code);
+            if (code = EscCode) or (code = CtrlCCode) then
+                break
+        end
+    end
 end.
+