Tried twice,  rebooted because Windows,  tried again,  same thing every time.   Game gets to "Game launched and ready",  music stops,  and then... nothing.   Loading screen hangs around,  I let it sit there for several minutes with no change.

Alt-F4 worked to close ES2,  so there was some part of the program still responding. 

Savegame attached.

UE - large normal.zip

Edit: diagnostics file attached

Diagnostics - 2017'06'24 @1741'43''.html

I looked at all three,  and they each ended with exactly the same lines:

17:42:47:755STACKGameClientState_GameLaunchedAndReady

17:42:47:858STACKAudio bank 'G_Soundscape_A' has been loaded.

17:42:47:858STACK[ChatMessage] RECV: l:/_launching/False (from 0x50badf5).

17:42:47:859STACK[ChatMessage] RECV: l:/_gameinprogress/True (from 0x50badf5).

17:42:47:859STACKGameServerState_Turn_Begin

17:42:47:859STACKIVisibilityService.AllowSendOrders(True)

17:42:48:248STACK[ShipDesignRenderer]  InitializeShipView:  this=/BackgroundRenderer/MilitaryScreen/MainContainer/ShipDesignOverviewPanel  currentViewIndex=0

17:42:49:667STACK[ShipDesignRenderer]  InitializeShipView:  this=/ModalRenderer/ShipDesignModalWindow/MainContainer/ShipDesignEditionPanel  currentViewIndex=1

17:42:49:733STACK[ShipDesignRenderer]  InitializeShipView:  this=/ModalRenderer/HeroInspectionModalWindow/MainContainer/HubPanels/HeroOverviewPanel/ShipDesignOverview  currentViewIndex=2

17:42:49:733STACK[ShipDesignRenderer]  InitializeShipView:  this=/ModalRenderer/HeroInspectionModalWindow/MainContainer/HubPanels/ShipDesignHolder/ShipDesignEditionPanel  currentViewIndex=3

Could you upload your Diagnostics File ?

It should be in %My Documents%\Endless Space 2\Temporary Files called something along the lines of "Diagnostics - Year'mm'dd @hhmm'ss''.html" 

The game makes one each time you run it, but only keeps the latest 10 so make sure you get the right one.

Edit:

Ok I've look at the diagnostis file and tried loading your save (I got the same result as you)

What I normally get after that point where the diagnostics stop is:

GameServerState_Turn_AI_Begin

GameServerState:Begin(System.Reflection.ParameterInfo) GameServerState_Turn_AI_Begin:Begin(System.Reflection.ParameterInfo) Amplitude.Unity.Framework.FiniteStateMachine:Update() GameInterface:Update() GameServer:Update() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

Open archive %Save Game File its loading%

AILoadRequestMessageRepository:TreatMessages(System.Reflection.ParameterInfo) AIMessageRepository`1[T]:Run() Amplitude.AI.Common.Threading.JobScheduler:WorkerThreadRun(System.Reflection.ParameterInfo)

Get ai serialization file from archive: 'ENFER.xml'.

AILoadRequestMessageRepository:TreatMessages(System.Reflection.ParameterInfo) AIMessageRepository`1[T]:Run() Amplitude.AI.Common.Threading.JobScheduler:WorkerThreadRun(System.Reflection.ParameterInfo)

Close archive %Save Game File its loading%

AILoadRequestMessageRepository:TreatMessages(System.Reflection.ParameterInfo) AIMessageRepository`1[T]:Run() Amplitude.AI.Common.Threading.JobScheduler:WorkerThreadRun(System.Reflection.ParameterInfo)

End of AI begin turn: Running

GameServerState_Turn_AI_Begin+c__Iterator0:MoveNext() Amplitude.Coroutine:Run() GameServerState_Turn_AI_Begin:Run() Amplitude.Unity.Framework.FiniteStateMachine:Update() GameInterface:Update() GameServer:Update() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

GameClientState_Turn_Begin

GameClientState:Begin(System.Reflection.ParameterInfo) GameClientState_Turn_Begin:Begin(System.Reflection.ParameterInfo) Amplitude.Unity.Framework.FiniteStateMachine:Update() GameInterface:Update() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

GameClientState_Turn_Main

GameClientState:Begin(System.Reflection.ParameterInfo) GameClientState_Turn_Main:Begin(System.Reflection.ParameterInfo) Amplitude.Unity.Framework.FiniteStateMachine:Update() GameInterface:Update() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

GameServerState_Turn_Main

GameServerState:Begin(System.Reflection.ParameterInfo) GameServerState_Turn_Main:Begin(System.Reflection.ParameterInfo) Amplitude.Unity.Framework.FiniteStateMachine:Update() GameInterface:Update() GameServer:Update() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

Change AI client state from None to Playing.

AIManager:ChangeAIClientState(System.Reflection.ParameterInfo) GameClient+c__Iterator0:MoveNext() Amplitude.Coroutine:Run() GameClient:ProcessOrders() GameInterface:UpdateMessageBoxAndProcessOrders() GameClient:UpdateMessageBoxAndProcessOrders() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

[Order] OrderUpdateVisibility::GameServer/OrderUpdateVisibility#00000006

Amplitude.Unity.Game.Orders.Order:Log() GameClient+c__Iterator52:MoveNext() Amplitude.Coroutine:Run() GameClient:ProcessOrders() GameInterface:UpdateMessageBoxAndProcessOrders() GameClient:UpdateMessageBoxAndProcessOrders() Session:Update() Amplitude.Unity.Session.SessionManager:LateUpdate()

Do you have any earlier saves from this game ?

Something is wrong with this save file or the way the game is trying to process it. I'm not a dev so I don't have too much detail on the process myself

An earlier save might help, Possibly.