how would i record if a player died in a game round or not?

Make a bool that sets to true when the round has started then use the plr.Humanoid.died() function. Once the player dies say if bool == true then to confirm a round is in session.

Wiki: http://wiki.roblox.com/index.php?title=API:Class/Humanoid/Died

-- example
bool = false

game.Players.PlayerAdded:connect(function(plr)
    plr.CharacterAdded:connect(function(chr)
        function roundstart()
            if bool == false then
                bool = true
            end
            wait(90) -- 1.5 mins
            -- do whatever else
        end

        function roundend()
            if bool == true then
                bool = false
            end
            wait(30)
            -- do whatever else
        end

        for i=1, math.huge() do
            roundstart()
            wait()
            roundend()
        end

        chr.Humanoid.Died:connect(function(player)
            if bool == true then
                ('ey')
            end
        end)
    end)
end)

• I kinda just wrote that on ze fly so it may be incorrect in some parts

What I would do is insert something into the player, such as a value. Once the players health => 0, then you make the value 1 or something. Check at the end of the game everyone's tags. If you a player has a 2 value, then the were still alive. If the value is 1, then they died. Just a suggestion, but I'm looking into it.