diff --git a/README.md b/README.md
index 13b3019..d8bb947 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,32 @@
 Python-based spaceship dodging game in terminal using curses (windows-curses), no pygame required.
 
+> Windows version of Python doesn't come with built-in module `curses`, but you can work around by using `windows-curses`
 
+### Linux
+
+```bash
+# unit test for windows
+conda env create -f environment.yml -n spaceship # env name
+conda activate spaceship
+# run the program
+python test.py --canvas_height 30 --canvas_width 30 --diff_level 2
+```
+
+demo
+
+<iframe width="857" height="565" src="https://www.youtube.com/embed/x4g7NjKTjqw" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
+### Windows
 
 ```bash
 # unit test for windows
 conda env create -f environment_win.yml -n spaceship # env name
 conda activate spaceship
-python test.py
+# run the program
+python test.py --canvas_height 30 --canvas_width 30 --diff_level 2
 ```
 
+demo
+
+![](https://i.loli.net/2021/05/14/i3oxKlQY9mcg74s.gif)
+
diff --git a/demo/demo.gif b/demo/demo_win.gif
similarity index 100%
rename from demo/demo.gif
rename to demo/demo_win.gif
diff --git a/environment.yml b/environment.yml
new file mode 100644
index 0000000..e1ea3cb
--- /dev/null
+++ b/environment.yml
@@ -0,0 +1,24 @@
+name: spaceship
+channels:
+  - defaults
+dependencies:
+  - _libgcc_mutex=0.1=main
+  - ca-certificates=2021.4.13=h06a4308_1
+  - certifi=2020.12.5=py39h06a4308_0
+  - ld_impl_linux-64=2.33.1=h53a641e_7
+  - libffi=3.3=he6710b0_2
+  - libgcc-ng=9.1.0=hdf63c60_0
+  - libstdcxx-ng=9.1.0=hdf63c60_0
+  - ncurses=6.2=he6710b0_1
+  - openssl=1.1.1k=h27cfd23_0
+  - pip=21.0.1=py39h06a4308_0
+  - python=3.9.4=hdb3f193_0
+  - readline=8.1=h27cfd23_0
+  - setuptools=52.0.0=py39h06a4308_0
+  - sqlite=3.35.4=hdfb4753_0
+  - tk=8.6.10=hbc83047_0
+  - tzdata=2020f=h52ac0ba_0
+  - wheel=0.36.2=pyhd3eb1b0_0
+  - xz=5.2.5=h7b6447c_0
+  - zlib=1.2.11=h7b6447c_3
+prefix: /home/luchaoqi/miniconda3/envs/spaceship
diff --git a/main.py b/main.py
index a8cbd28..59cf2f1 100644
--- a/main.py
+++ b/main.py
@@ -79,7 +79,7 @@ def main(nlines=10,ncols=30,begin_y=0,begin_x=0,difficulty=2):  # sourcery no-me
     parser.add_argument("--canvas_width", nargs='?', default=30, type=int,help="width of canvas")
     parser.add_argument("--begin_y", nargs='?', default=0, type=int,help="position of upper margin of canvas")
     parser.add_argument("--begin_x", nargs='?', default=0, type=int,help="position of left margin of canvas")
-    parser.add_argument("--diff_level", nargs='?', default=1, type=int, choices=[0,1,2], help="difficulty level: control the number of obstacles/move speed")
+    parser.add_argument("--diff_level", nargs='?', default=1, type=int, choices=[0,1,2], help="difficulty level: control the number of obstacles/move speed. Choices = [0,1,2]. Defaults to 2")
     args = parser.parse_args()
 
     main(nlines=args.canvas_height,ncols=args.canvas_width,difficulty=args.diff_level)
\ No newline at end of file