diff --git a/src/abstractenv.jl b/src/abstractenv.jl
index 97d8c7b..44ac680 100644
--- a/src/abstractenv.jl
+++ b/src/abstractenv.jl
@@ -20,6 +20,21 @@ function action_space end
 function observation_space end
 function render end
 
+"""
+    Observation(;reward, terminal, state, meta...)
+
+The observation of an environment from the perspective of an agent.
+
+# Keywords & Fields
+
+- `reward`: the reward of an agent
+- `terminal`: indicates that if the environment is terminated or not.
+- `state`: the current state of the environment from the perspective of an agent
+- `meta`: some other information, like `legal_actions`...
+
+!!! note
+    The `reward` and `terminal` of the first observation before interacting with an environment may not be valid.
+"""
 struct Observation{R,T,S,M<:NamedTuple}
     reward::R
     terminal::T
diff --git a/src/environments/atari.jl b/src/environments/atari.jl
index 16827cf..9279588 100644
--- a/src/environments/atari.jl
+++ b/src/environments/atari.jl
@@ -1,93 +1,136 @@
-using ArcadeLearningEnvironment, GR
+using ArcadeLearningEnvironment, GR, Random
 
 export AtariEnv
 
-mutable struct AtariEnv{To,F} <: AbstractEnv
+mutable struct AtariEnv{IsGrayScale, TerminalOnLifeLoss, N, S<:AbstractRNG} <: AbstractEnv
     ale::Ptr{Nothing}
-    screen::Array{UInt8,1}
-    getscreen!::F
-    actions::Array{Int64,1}
+    screens::Tuple{Array{UInt8, N}, Array{UInt8, N}}  # for max-pooling
+    actions::Vector{Int64}
     action_space::DiscreteSpace{Int}
-    observation_space::To
+    observation_space::MultiDiscreteSpace{UInt8, N}
     noopmax::Int
+    frame_skip::Int
     reward::Float32
+    lives::Int
+    seed::S
 end
 
 """
-    AtariEnv(name; colorspace = "Grayscale", frame_skip = 4, noopmax = 20,
-                   color_averaging = true, repeat_action_probability = 0.)
-Returns an AtariEnv that can be used in an RLSetup of the
-[ReinforcementLearning](https://github.com/jbrea/ReinforcementLearning.jl)
-package. Check the deps/roms folder of the ArcadeLearningEnvironment package to
-see all available `name`s.
+    AtariEnv(;kwargs...)
+
+This implementation follows the guidelines in [Revisiting the Arcade Learning Environment: Evaluation Protocols and Open Problems for General Agents](https://arxiv.org/abs/1709.06009)
+
+TODO: support seed! in single/multi thread
+
+# Keywords
+
+- `name::String="pong"`: name of the Atari environments. Use `getROMList` to show all supported environments.
+- `grayscale_obs::Bool=true`:if `true`, then gray scale observation is returned, otherwise, RGB observation is returned.
+- `noop_max::Int=30`: max number of no-ops.
+- `frame_skip::Int=4`: the frequency at which the agent experiences the game.
+- `terminal_on_life_loss::Bool=false`: if `true`, then game is over whenever a life is lost.
+- `repeat_action_probability::Float64=0.`
+- `color_averaging::Bool=false`: whether to perform phosphor averaging or not.
+- `max_num_frames_per_episode::Int=0`
+- `full_action_space::Bool=false`: by default, only use minimal action set. If `true`, one need to call `legal_actions` to get the valid action set. TODO
+
+See also the [python implementation](https://github.com/openai/gym/blob/c072172d64bdcd74313d97395436c592dc836d5c/gym/wrappers/atari_preprocessing.py#L8-L36)
 """
 function AtariEnv(
-    name;
-    colorspace = "Grayscale",
+    ;name = "pong",
+    grayscale_obs=true,
+    noop_max = 30,
     frame_skip = 4,
-    noopmax = 20,
-    color_averaging = true,
-    actionset = :minimal,
-    repeat_action_probability = 0.,
+    terminal_on_life_loss=false,
+    repeat_action_probability=0.,
+    color_averaging=false,
+    max_num_frames_per_episode=0,
+    full_action_space=false,
+    seed=nothing
 )
+    frame_skip > 0 || throw(ArgumentError("frame_skip must be greater than 0!"))
+    name in getROMList() || throw(ArgumentError("unknown ROM name! run `getROMList()` to see all the game names."))
+
+    if isnothing(seed)
+        seed = (MersenneTwister(), 0)
+    elseif seed isa Tuple{Int, Int}
+        seed = (MersenneTwister(seed[1]), seed[2])
+    else
+        @error "You must specify two seeds, one for Julia wrapper, one for internal C implementation" # ??? maybe auto generate two seed from one
+    end
+
     ale = ALE_new()
-    setBool(ale, "color_averaging", color_averaging)
-    setInt(ale, "frame_skip", Int32(frame_skip))
+    setInt(ale, "random_seed", seed[2])
+    setInt(ale, "frame_skip", Int32(1))  # !!! do not use internal frame_skip here, we need to apply max-pooling for the latest two frames, so we need to manually implement the mechanism.
+    setInt(ale, "max_num_frames_per_episode", max_num_frames_per_episode)
     setFloat(ale, "repeat_action_probability", Float32(repeat_action_probability))
+    setBool(ale, "color_averaging", color_averaging)
     loadROM(ale, name)
-    observation_length = getScreenWidth(ale) * getScreenHeight(ale)
-    if colorspace == "Grayscale"
-        screen = Array{Cuchar}(undef, observation_length)
-        getscreen! = ArcadeLearningEnvironment.getScreenGrayscale!
-        observation_space = MultiDiscreteSpace(
-            fill(typemax(Cuchar), observation_length),
-            fill(typemin(Cuchar), observation_length),
-        )
-    elseif colorspace == "RGB"
-        screen = Array{Cuchar}(undef, 3 * observation_length)
-        getscreen! = ArcadeLearningEnvironment.getScreenRGB!
-        observation_space = MultiDiscreteSpace(
-            fill(typemax(Cuchar), 3 * observation_length),
-            fill(typemin(Cuchar), 3 * observation_length),
-        )
-    elseif colorspace == "Raw"
-        screen = Array{Cuchar}(undef, observation_length)
-        getscreen! = ArcadeLearningEnvironment.getScreen!
-        observation_space = MultiDiscreteSpace(
-            fill(typemax(Cuchar), observation_length),
-            fill(typemin(Cuchar), observation_length),
-        )
-    end
-    actions = actionset == :minimal ? getMinimalActionSet(ale) : getLegalActionSet(ale)
+
+    observation_size = grayscale_obs ? (getScreenWidth(ale), getScreenHeight(ale)) : (3, getScreenWidth(ale), getScreenHeight(ale))  # !!! note the order
+    observation_space = MultiDiscreteSpace(
+        fill(typemax(Cuchar), observation_size),
+        fill(typemin(Cuchar), observation_size),
+    )
+
+    actions = full_action_space ? getLegalActionSet(ale) : getMinimalActionSet(ale)
     action_space = DiscreteSpace(length(actions))
-    AtariEnv(
+    screens = (
+        fill(typemin(Cuchar), observation_size),
+        fill(typemin(Cuchar), observation_size),
+    )
+
+    AtariEnv{grayscale_obs, terminal_on_life_loss, grayscale_obs ? 2 : 3, typeof(seed[1])}(
         ale,
-        screen,
-        getscreen!,
+        screens,
         actions,
         action_space,
         observation_space,
-        noopmax,
+        noop_max,
+        frame_skip,
         0.0f0,
+        lives(ale),
+        seed[1]
     )
 end
 
-function interact!(env::AtariEnv, a)
-    env.reward = act(env.ale, env.actions[a])
-    env.getscreen!(env.ale, env.screen)
+update_screen!(env::AtariEnv{true}, screen) = ArcadeLearningEnvironment.getScreenGrayscale!(env.ale, vec(screen))
+update_screen!(env::AtariEnv{false}, screen) = ArcadeLearningEnvironment.getScreenRGB!(env.ale, vec(screen))
+
+function interact!(env::AtariEnv{is_gray_scale, is_terminal_on_life_loss}, a) where {is_gray_scale, is_terminal_on_life_loss}
+    r = 0.0f0
+
+    for i in 1:env.frame_skip
+        r += act(env.ale, env.actions[a])
+        if i == env.frame_skip
+            update_screen!(env, env.screens[1])
+        elseif i == env.frame_skip - 1
+            update_screen!(env, env.screens[2])
+        end
+    end
+
+    # max-pooling
+    if env.frame_skip > 1
+        env.screens[1] .= max.(env.screens[1], env.screens[2])
+    end
+
+    env.reward = r
     nothing
 end
 
-observe(env::AtariEnv) =
-    Observation(reward = env.reward, terminal = game_over(env.ale), state = env.screen)
+is_terminal(env::AtariEnv{<:Any, true}) = game_over(env.ale) || (lives(env.ale) < env.lives)
+is_terminal(env::AtariEnv{<:Any, false}) = game_over(env.ale)
+
+observe(env::AtariEnv) = Observation(reward = env.reward, terminal = is_terminal(env), state = env.screens[1])
 
 function reset!(env::AtariEnv)
     reset_game(env.ale)
-    for _ = 1:rand(0:env.noopmax)
+    for _ = 1:rand(env.seed, 0:env.noopmax)
         act(env.ale, Int32(0))
     end
-    env.getscreen!(env.ale, env.screen)
+    update_screen!(env, env.screens[1])  # no need to update env.screens[2]
     env.reward = 0.0f0  # dummy
+    env.lives = lives(env.ale)
     nothing
 end
 
diff --git a/test/atari.jl b/test/atari.jl
new file mode 100644
index 0000000..310309c
--- /dev/null
+++ b/test/atari.jl
@@ -0,0 +1,75 @@
+@testset "atari" begin
+    @testset "seed" begin
+        env = AtariEnv(;name="pong", seed=(123,456))
+        old_states = []
+        actions = [rand(action_space(env)) for i in 1:10, j in 1:100]
+
+        for i in 1:10
+            for j in 1:100
+                interact!(env, actions[i, j])
+                push!(old_states, copy(observe(env).state))
+            end
+            reset!(env)
+        end
+
+        env = AtariEnv(;name="pong", seed=(123,456))
+        new_states = []
+        for i in 1:10
+            for j in 1:100
+                interact!(env, actions[i, j])
+                push!(new_states, copy(observe(env).state))
+            end
+            reset!(env)
+        end
+
+        @test old_states == new_states
+    end
+
+    @testset "frame_skip" begin
+        env = AtariEnv(;name="pong", frame_skip=4, seed=(123,456))
+        states = []
+        actions = [rand(action_space(env)) for _ in 1:100]
+
+        for i in 1:100
+            interact!(env, actions[i])
+            push!(states, copy(observe(env).state))
+        end
+
+        env = AtariEnv(;name="pong", frame_skip=1, seed=(123,456))
+        for i in 1:100
+            interact!(env, actions[i])
+            interact!(env, actions[i])
+            interact!(env, actions[i])
+            s1 = copy(observe(env).state)
+            interact!(env, actions[i])
+            s2 = copy(observe(env).state)
+            @test states[i] == max.(s1, s2)
+        end
+    end
+
+    @testset "repeat_action_probability" begin
+        env = AtariEnv(;name="pong", repeat_action_probability=1.0, seed=(123,456))
+        states = []
+        actions = [rand(action_space(env)) for _ in 1:100]
+        for i in 1:100
+            interact!(env, actions[i])
+            push!(states, copy(observe(env).state))
+        end
+
+        env = AtariEnv(;name="pong", repeat_action_probability=1.0, seed=(123,456))
+        for i in 1:100
+            interact!(env, actions[1])
+            @test states[i] == observe(env).state
+        end
+    end
+
+    @testset "max_num_frames_per_episode" begin
+        for i in 1:10
+            env = AtariEnv(;name="pong", max_num_frames_per_episode=i, seed=(123,456))
+            for _ in 1:i
+                interact!(env, 1)
+            end
+            @test true == observe(env).terminal
+        end
+    end
+end
\ No newline at end of file
diff --git a/test/environments.jl b/test/environments.jl
index 914fca3..83330cf 100644
--- a/test/environments.jl
+++ b/test/environments.jl
@@ -62,7 +62,7 @@
         :(deterministic_tree_MDP_with_rand_reward()),
         :(deterministic_tree_MDP()),
         :(deterministic_MDP()),
-        (:(AtariEnv($x)) for x in atari_env_names)...,
+        (:(AtariEnv(;name=$x)) for x in atari_env_names)...,
         (:(GymEnv($x)) for x in gym_env_names)...,
     ]
 
diff --git a/test/runtests.jl b/test/runtests.jl
index 8687c0d..b18c533 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -10,5 +10,5 @@ using Hanabi
 
     include("spaces.jl")
     include("environments.jl")
-
+    include("atari.jl")
 end
\ No newline at end of file