With the recent technological evolutions in networks and increased deployment of multi-tier clouds, cloud gaming (CG) is gaining renewed interest and is expected to become a major Internet service in the upcoming years. Many companies have launched powerful platforms such as Google Stadia, Nvidia GeForce Now, Microsoft xCloud, Sony PlayStation Now among others, to attract players. However, for all end-users to fully enjoy their gaming sessions over the wide range of network access qualities, CG platforms must adapt their traffic. In this paper, we present the outcome of real-life measurements performed between April and July 2021 on the four aforementioned CG platforms, configuring different network constraints like packet loss, throughput decrease, latency increase and jitter variation to observe the behavior of these CG platforms under extreme network conditions. Our findings show that the four platforms exhibit different adaptation behaviors. Moreover, many cases result in a degraded QoS, leaving room for further improvements at both application and/or network levels.