SQL Server 2019

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table PlayTime
(
  AccountId int,
  GameId nvarchar(20),
  Actions numeric(5,1)
);

insert into PlayTime (AccountId, GameId, Actions) values
(611525, '771', 0.4),
(611525, '82244', 11.5),
(611525, '82246', 4),
(611525, '81400039', 15),
(1000029, '78884', 30),
(1000029, '98889', 100),
(1000040, 'orjyqvinjm3xsp6y', 120),
(1000040, '82200105', 180),
(1000040, '82245', 2),
(1000040, '82254', 7),
(1000040, '82244', 8),
(1000040, '82242', 27),
(1000040, 'instantgame', 1),
(1000060, '82264', 1),
(1000060, '137000058', 1),
(1000060, '82200064', 229),
(1000083, '82254', 109.4),
(1000083, '82264', 19.5),
(1000083, '82243', 6),
(1000103, '80758', 1.5),
(1000103, '82245', 51),
(1000103, '82200125', 300),
(1000103, '81400044', 0.7);

select * from PlayTime;


AccountId
GameId
Actions


611525
771
0.4

611525
82244
11.5

611525
82246
4.0

611525
81400039
15.0

1000029
78884
30.0

1000029
98889
100.0

1000040
orjyqvinjm3xsp6y
120.0

1000040
82200105
180.0

1000040
82245
2.0

1000040
82254
7.0

1000040
82244
8.0

1000040
82242
27.0

1000040
instantgame
1.0

1000060
82264
1.0

1000060
137000058
1.0

1000060
82200064
229.0

1000083
82254
109.4

1000083
82264
19.5

1000083
82243
6.0

1000103
80758
1.5

1000103
82245
51.0

1000103
82200125
300.0

1000103
81400044
0.7


-- SQL Server 2017 and later
with cte as
(
  select pt.AccountId,
         pt.GameId,
         row_number() over(partition by pt.AccountId order by pt.Actions desc) as RowNum
  from PlayTime pt
)
select cte.AccountId,
       string_agg(cte.GameId, ',') as TopGames
from cte
where cte.RowNum <= 3
group by cte.AccountId
order by cte.AccountId;


AccountId
TopGames


611525
81400039,82244,82246

1000029
98889,78884

1000040
82200105,orjyqvinjm3xsp6y,82242

1000060
82200064,82264,137000058

1000083
82254,82264,82243

1000103
82200125,82245,80758


-- Before SQL Server 2017
with cte as
(
  select pt.AccountId,
         pt.GameId,
         row_number() over(partition by pt.AccountId order by pt.Actions desc) as RowNum
  from PlayTime pt
)
select p.AccountId,
       p.[1] + case when p.[2] is not null then ',' + p.[2] else '' end
             + case when p.[3] is not null then ',' + p.[3] else '' end as TopGames
from cte
pivot (max(cte.GameId) for cte.RowNum in ([1], [2], [3])) p
order by p.AccountId;


AccountId
TopGames


611525
81400039,82244,82246

1000029
98889,78884

1000040
82200105,orjyqvinjm3xsp6y,82242

1000060
82200064,82264,137000058

1000083
82254,82264,82243

1000103
82200125,82245,80758

AccountId	GameId	Actions
611525	771	0.4
611525	82244	11.5
611525	82246	4.0
611525	81400039	15.0
1000029	78884	30.0
1000029	98889	100.0
1000040	orjyqvinjm3xsp6y	120.0
1000040	82200105	180.0
1000040	82245	2.0
1000040	82254	7.0
1000040	82244	8.0
1000040	82242	27.0
1000040	instantgame	1.0
1000060	82264	1.0
1000060	137000058	1.0
1000060	82200064	229.0
1000083	82254	109.4
1000083	82264	19.5
1000083	82243	6.0
1000103	80758	1.5
1000103	82245	51.0
1000103	82200125	300.0
1000103	81400044	0.7

AccountId	TopGames
611525	81400039,82244,82246
1000029	98889,78884
1000040	82200105,orjyqvinjm3xsp6y,82242
1000060	82200064,82264,137000058
1000083	82254,82264,82243
1000103	82200125,82245,80758