Explanation of my strategy and thought process in chronological order

After seeing Vanilla_Cabs's comment I lied to them about wanting to join the clique. I was undecided, but I figured seeing the code of the clique can be a great advantage if I can exploit some coding mistake and I can still decide to join later anyway if I want.

The first versions of CloneBot (the name of the program for our clique) did actually contain a mistake I could exploit (by defining the __new__() method of the class after the payload) and so this was my plan until Vanilla_Cabs fixed this mistake. After they fixed it, I didn't notice any way I can take advantage, so I joined the clique in spirit.

Initially my plan for my bot was a simulator which simulates between 100 and 1000 turns of the opponent against a few candidate bots (ZviBot, TiTforTat, return 3, return 2, etc..) and then depending on the round number either chooses the one with the maximum point for me or the one which gets more points than the opponent. There were unfortunately two problems with this plan:

1. Bots who can detect if they are in a simulation can get me into an infinite loop which would disqualify my program, so I had to research the ways this might happen to know how to prevent it. I started by inspecting the code for AbstractTreeSpyBot and I did notice some ways to do this:
   • The code always instantiates a new object, so by storing past moves, I can detect if I'm in a simulation if my move() method's argument is not None and I have not stored previous moves. This defect however is really specific to this program and other simulators can easily avoid it by storing the instantiated class object between rounds.
   • The code simply calls the simulated bot's move() method which can be detected by inspecting the call stack and finding a local variable named 'self' with a method named 'move' of a class type not named the simulated bot's classname. This method of detection can still be tricked by running the simulation in a different process (eg by calling the python interpreter from the shell, this has the advantage of having an easy and robust way to redefine get_opponent_source()), but still I expect this would DQ many submitted simulators. (I attached the code of a bot using this type of detection.)
2. Isusr posted a very unforgiving time limit. Unfortunately, I could not make simulator bot work in this timelimit. In fact, on my laptop even AbstractSpyTreeBot does not run in 0.05s (1 init + 100 moves) and to avoid detection I would have to call the python interpreter from the os which would again cost a lot of time. It does not even matter what the time limit is just that it is not a vague 'don't be too slow' like it was initially, because I planned to simulate (100-1000 moves+init)*(number of programs I want to try), so if the number of programs I want to try is greater than 1 I would go over the limit if my opponent uses even just half the limit.

After this, seeing that I can't make my simulator work, I abandoned the idea of me submitting a simulator. However seeing that some other types of simulator can still be pretty strong, I decided to disincentivize them, so when Larian cautioned in the clique-chat that simulator crashing bots weaken our clique (as isusr restarts the whole tournament in the event of DQ), so we should not use them, I lied that I've already submitted one program detecting and crashing simulators. Of course Larian's point was valid, so obviously I did not even plan to do so. Some time later It occured to me that my claim that there is a simulator crashing bot in the clique might incentivize those who wanted to submit a simulator to leave the clique, so I added another lie that the method of detecting simulators was my friend's idea (hopefully suggesting that there is another contestant with the same method outside the clique). I'm curious how believable my lies were, I felt them to be pretty weak, hopefully it's only because of my inside view.

After this I had to come up with an actual program. My intrigue and life didn't leave me with much time, so I finally submitted a ZviBot (a bot similar to the one described in the Darwin Game series) as a payload (for those not in our clique: payload is the part of the CloneBot which activates in the endgame against other clique members). While I did not have time to run simulations, I had three reasons for this submission:

1. ZviBot has a good track record in a similar competition.
2. Given that bots in this competition know the round number, I expect that many will get meaner (less cooperating) in the later rounds on the grounds that if they survived for this many rounds they are probably a significant portion of the pool, so they can try to kill others. However because the programs will use different rates of becoming uncooperating, they will get eliminated from the pool one by one as the others are still cooperatating. By not getting meaner my plan was to stay in the final equilibrium state with others.
3. I was curious how such a simple bot would perform.

Bot detecting simulators:

class MatrixCrashingBot():
    def __init__(self, round=1):
       import inspect
       from time import sleep
       sf = inspect.stack()
       simulated = False
       enemy = ""
       for f in sf:
           if ('self' not in f.frame.f_locals):
               continue
           fo = f.frame.f_locals['self']
           fod = dict(inspect.getmembers(fo))
           if 'MatrixCrashingBot' != fo.__class__.__name__ and 'move' in fod:
               simulated = True
               enemy = fo.__class__.__name__
               break
       if simulated:
           while 1:
               print("{} tried to simulate me :O >:\[ So I sent him to an infinite cycle!\nNote to the tournament organizer: The infinite cycle is run by {} not by the MatrixCrashingBot! ".format(enemy, enemy))
               sleep(3)  
    def move(self, previous=None):
        return 3

Bot I finally submitted: (everything exept the payload is written by Vanilla_cabs. The core idea (alternating 3s and 2s) of the payload is from Zvi)

class CloneBot():
    def __init__(self, round=0):
        import math
        import random
        import extra
        self.math = math
        self.random = random
        self.extra = extra

        self.showdownRound = 90     # after this round, your personal program takes over
        self.round = round          # the current round
        self.myMoves = []           # all the moves you've made, first to last
        self.opponentMoves = []     # all the moves your opponent has made, first to last

        my_source_raw = extra.__getattribute__(''.join(['ge','t_','my','_s','ou','rce']))(self)
        opponent_source_raw = extra.__getattribute__(''.join(['ge','t_','op','po','ne','nt','_s','ou','rce']))(self)
        my_source = "\n".join(["    ".join(line.split('\t')).rstrip() for line in my_source_raw.splitlines()])
        opponent_source = "\n".join(["    ".join(line.split('\t')).rstrip() for line in opponent_source_raw.splitlines()])

        if not 'def payload(self) :' in opponent_source :
            self.is_opponent_clone = False
        else :
            my_common_code, my_payload = my_source.rsplit('def payload(self) :', 1)
            opponent_common_code, opponent_payload = opponent_source.rsplit('def payload(self) :', 1)
            if my_common_code != opponent_common_code :
                self.is_opponent_clone = False
            else :
                self.is_opponent_clone = True
                for line in opponent_payload.split("\n") :
                    # checks that no common method or property is overwritten after the payload
                    # allows the innocuous command "foo = 'bar'" by member's demand
                    if line.lstrip() != "" and line != "foo = 'bar'" and line[0:8] != "        " :
                        self.is_opponent_clone = False
                        break

            if self.is_opponent_clone :
                payload_length_difference = len(my_payload) - len(opponent_payload)
                if my_payload != opponent_payload :
                    # compares payloads without reading them
                    # fair way to decide who starts with 3 between two clones
                    # for 100% protection against ties, personalize your payload with a comment
                    self.high_first = (my_payload < opponent_payload) == ((payload_length_difference+round) % 2 == 1)
            
    def move(self, previous=None) :
        self.turn = len(self.myMoves)               # the current turn
        # pseudorandom to allow simulators to collaborate
        self.random.seed((self.round+1) * (self.turn+1) * (7 if previous==None else (previous+1)))
        
        if previous != None :
            self.opponentMoves.append(previous)
        if self.is_opponent_clone :
            if self.round < self.showdownRound :
                output = self.cooperateWithClone()
            else :
                output = self.payload()
        else :
            output = self.default()
        self.myMoves.append(output)
        return output

    def defaultCooperation(self) :              # factor influencing behaviour with non-clones, 1 at round 0, 0 at round 60
        return max(0.0, float(self.showdownRound - (self.round*1.5)) / self.showdownRound)
        
    def cooperateWithClone(self) :
        if self.turn == 0 :
            if self.high_first :
                return 3
            else :
                return 2
        else :
            return self.opponentMoves[-1]

    def default(self) :
        if self.turn == 0 :
            if self.random.random() < 0.5 * self.defaultCooperation() :
                return 2
            else :
                return 3
        elif self.myMoves[-1] + self.opponentMoves[-1] == 5 :
            if self.myMoves[-1] == 2 :
                return 3                        # tit for tat
            elif self.myMoves[-1] == 3 :
                if self.turn >= 2 :
                    if self.myMoves[-2] == 3 and self.opponentMoves[-2] == 2 :
                        return 3                # stable 3 against 2
                if self.random.random() < self.defaultCooperation() * 1.2 :
                    return 2                    # cooperation
                else :
                    return 3                    # maintain 3 against 2
            else :
                return self.myMoves[-1]         # free candy
        elif self.myMoves[-1] + self.opponentMoves[-1] < 5 :
            return 5 - self.opponentMoves[-1]
        else :                                  # sum > 5
            if self.random.random() < self.defaultCooperation() * max(0, 50-self.turn) / 100.0 :
                return 2                        # back down
            else :
                return 3                        # maintain
    
    def payload(self) :
        # put a personal word here to guarantee no tie during cooperation: in a pretty body no one can see your rotten soul
        # put what you want to play for the showdown
        # no line after 'def payload(self)' should have less than 8 whitespaces at the beginning,
        # unless it's an empty or only whitespace line
        #
        # Idea of solution: most program will gradually get meaner as rounds
        # progress, but because they do so at different rates
        # they will get eliminated as other, still cooperating bots outcompete their
        # meanness. By not getting meaner I plan to stay in the final equilibrium state.
        # Otherwise it's a ZviBot.
        if self.turn == 0:
            self.switched = False
            return 3
        else:
            # against very submissive bots
            if self.turn >= 3 and self.opponentMoves[-1] < 3 and self.opponentMoves[-2] < 3 and self.opponentMoves[-3] < 3:
                return 5-self.opponentMoves[-1]
            # against bots who are very bad at detecting patterns
            if self.turn >= 5 and self.opponentMoves[-1] == 3 and self.opponentMoves[-2] == 2 and self.opponentMoves[-3] == 3 and \
                    self.myMoves[-1] == 3 and self.myMoves[-2] == 2 and self.myMoves[-3] == 3 and not self.switched:
                self.switched = True
                return 3;
            if self.myMoves[-1] == 2:
                return 3
            elif self.myMoves[-1] == 3:
                return 2