Here is a ranking of kills per root game where the top 100 scorers were ranked by absolute number of kills, the bottom three of these removed, and replaced with the three non-top-100 leaders in kills on the leaderboard.

Compiling this list is a pain in the butt because the non-top-100 scorers on the kill leaderboard have to found in the live leaderboard (which tends to lag real time) and copied and pasted one at a time into my spreadsheet and the regular top scorers can be loaded in only 25 at a time and during this process they may jump around in rank and end up twice in the list. So I am doing this only this once. But here is the list:

9.32 stakaboo
9.09 Preston
9.00 simor10
8.80 dnaa
8.76 fgfx
8.51 wertrew
7.59 Mikkis
7.47 avesano
7.20 Qazi Legend
6.63 JamesEnsor
6.37 48430934809
6.30 S3Z0
6.19 saltari
6.12 queerer
6.12 queerer
5.72 Beach_Bum_13
5.66 Kludge26
5.63 Omarinho
5.56 Harlequin UZ
5.42 Bigusdickus
5.35 AI7
5.14 Ferrum
4.98 MNML
4.94 Dude111
4.87 Volvic
4.76 Magno 123
4.75 iIlest
4.66 kapouaii
4.64 caligula1
4.64 @HarunKavun
4.64 tetyos
4.58 Adam Candee
4.57 Gummitarsan
4.52 dicebomb
4.45 NardSausage
4.38 22 Apr
4.32 rofarah
4.30 AlexBallDrop
4.30 bongoman
4.29 Bart Lee
4.25 Az_Balu
4.23 Joep Eerlijk
4.10 Louis Cypher
4.07 Tommy Simpson
3.97 Havefun45
3.92 MCI
3.90 nada01
3.89 Ax Cx
3.88 Rastaa Man :)
3.82 ShogoKawada[BR]
3.82 Top Kapi
3.81 danikbl
3.75 SmokingJoker
3.75 Condoleezza Dice
3.67 ovbogaert
3.50 kdiceplaya!
3.50 flizza
3.35 greeen
3.35 masticore
3.34 captainLAGER
3.32 marks13
3.27 tantywhu
2.99 gameboy
2.87 Plokijuma
2.83 shirahoshi
2.70 joejoewhoa
2.56 Nerd Alert
2.55 Three_Blind_Dice
2.54 mr.deef
2.51 spman2
2.46 Cameron Lucas
2.31 saulens
2.24 happytoscrap
2.21 DiceMan3000
2.21 piers plowman
2.19 @chrisXBT
2.14 spman
2.08 strzala91
2.00 spman3
1.98 Stockli
1.94 jurgen
1.91 Naughty1
1.84 Jebonah
1.80 Nicker_
1.80 Mitsi the cat
1.79 Loobee
1.79 moulue
1.69 sews4wampum
1.58 BenJa LeZana
1.50 spman5
1.38 DonnieScribbles
1.33 Arnas Bro
1.24 FreiWild
1.17 farq
0.97 Easy A
0.90 wool
0.58 ivv
0.50 orestis85
0.45 Distorted

Preston, simor10, and Mikkis show up in the top 10 deadliest players.